Check automatic line feed failure ID: lst300-feed-failure Version: 2.0.0 Model: BLACK+DECKER LST300 · US · AF-100 Region: US Parts: Automatic-feed head with AF-100 spool; match model and tool type to manual Not covered: LST420 / LSTE525; GH corded models; Dual-line heads; Metal line or blades; Nonmatching tool type or modified head; Unknown tool type or missing exact-type manual; Bump-feed conversion MATCH YOUR VERSION Model and tool type: LST300 and the exact type on my label match my manufacturer manual and figures Remove the battery before finding the label. Use the manufacturer model-and-type lookup; this site does not infer a type number from LST300 alone. Cutting head: Original AF-100 automatic-feed single-line head Do not substitute a bump-feed procedure, dual-line spool or metal cutting attachment. PREPARE [ ] Release the trigger, let the head stop, engage the lock-off and remove the battery. Leave it removed throughout hands-on care. Keep fingers away from the sharp cutter on the guard. [ ] Read LST300 and the tool type from the label. Open the official model/type lookup and compare its manual and parts figures with your actual guard, single-line head and AF-100 spool. A readable model name alone does not establish the type. If the exact type manual cannot be obtained, or any figure differs, save a preparation record and stop. [ ] Tool: Good lighting [ ] Tool: Scissors for nylon only [ ] Material: Compatible AF-100 spool only if current line is insufficient STOP Keep the battery removed if the exact type/manual match is unknown or parts differ from the figures. Stop for a damaged battery, exposed wiring, a faulty switch, cracked guard, broken spool/hub, damaged cap tabs or housing slots. Use an authorized service center. Never open the battery, motor housing or charger. CONSUMABLE FIT Factory-wound replacement spool: BLACK+DECKER AF-100; 0.065 inch (1.65 mm) round nylon monofilament Fit: Original LST300 automatic single-line head, after exact tool-type/manual match Do not substitute: Bump-feed or dual-line heads; metal, serrated or heavier line; unverified replacement heads Source: lst300-manual, English p9 Cutting line / Line feeding; Replacement accessories Bulk cutting line: 0.065 inch (1.65 mm) round nylon monofilament Fit: Intact original AF-100 spool with the slot, adjacent anchor hole, arrow and fill recesses in figs P–R Do not substitute: Serrated, square, heavier or metal line; different anchor geometry Source: lst300-manual, English p10 Rewinding spool from bulk line; figs P–R CHECK ROUTE safety: Is the battery removed, the trigger released and the cutting head stopped, with no battery damage, exposed wiring or faulty switch? Yes -> compatibility: Keep the battery removed for every hands-on step. No -> service: Stop using the tool for electrical, battery or switch damage. If you have only omitted battery removal, make the tool safe before restarting. Not sure -> prepared: Keep the battery removed. Save your preparation record and check the matching manual before continuing. compatibility: Have you matched the label LST300 AND its exact tool type to the official lookup manual and its figures, with the original AF-100 automatic single-line head? Yes -> check-1: Record the label type and matching manual reference in the first step. No -> prepared: An unknown type, unavailable type manual, different figures, bump-feed head or dual-line conversion blocks this procedure. Use manufacturer support to identify the correct instructions. Not sure -> prepared: Keep the battery removed. Save your preparation record and check the matching manual before continuing. check-1: Was the observed problem failure to advance line on the original automatic-feed head? Yes -> check-2: Never bump this head to attempt a feed. No -> prepared: Use the slow-running or cap-latch task for those different symptoms. Not sure -> prepared: Keep the battery removed. Save your preparation record and check the matching manual before continuing. check-2: Are the cap, guard and housing intact and the remaining line the specified round nylon? Yes -> steps: Check remaining line and the winding first. No -> service: Damaged parts require service; verify an unknown line specification before continuing. Not sure -> prepared: Keep the battery removed. Save your preparation record and check the matching manual before continuing. CARE STEPS (only when the route reaches steps) [ ] 1. Record the exact tool and make it safe Release the trigger, let the head stop, engage the lock-off and remove the battery. Leave it removed throughout hands-on care. Keep fingers away from the sharp cutter on the guard. Read LST300 and the tool type from the label. Open the official model/type lookup and compare its manual and parts figures with your actual guard, single-line head and AF-100 spool. A readable model name alone does not establish the type. If the exact type manual cannot be obtained, or any figure differs, save a preparation record and stop. Look for: The battery is physically separate from the tool; your label type and matching manual reference are written below. Source: bd-manual-help, Official model/type lookup instructions; type is beside or below the model number [ ] 2. Open and record the line condition Release the cap tabs and remove the cap with the battery out. Note whether line remains on the spool, is crossed or knotted, or has retracted inside the eyelet. Do not pull hard against a jam. Look for: You have recorded what is visible before changing the winding. Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R [ ] 3. Choose the supply remedy If too little usable line remains, fit a compatible AF-100 using the spool task. If adequate line remains, pull it gently to approximately 5-3/8 inches (136 mm). Stop pulling if it binds; lift out the spool for inspection. Look for: There is enough compatible line, or a replacement task has been identified. Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R [ ] 4. Check winding and its anchor Look for crossed layers and check that the beginning of the line is held tight against the spool as fig Q shows. Correct a hand-wound spool only with the full figs P–R rewind sequence, or use factory-wound AF-100. Look for: Line layers do not cross and the anchor is tight; no generic anchor method is substituted. Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R [ ] 5. Check the exposed feed lever With the spool removed, carefully clear loose grass and dirt from the housing. Check that the lever can move freely without force and matches fig N. Do not remove the lever for cleaning, add lubricant or open the motor. Look for: The lever moves freely and is in its pictured position; stiffness or damage is recorded for service. Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R [ ] 6. Refit and limit the line Route the single line through the eyelet, seat the spool on its boss and latch both cap tabs. Shorten any nylon that extends past the guard cutter so it just reaches the cutter. Look for: The cap is secure, line path is clear and the line is not overlong. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O [ ] 7. Save the cause found and next check Record which condition you corrected. Use Verify the trimmer after maintenance for a normal-use test. If feeding still fails after correct winding and cleaning, stop and contact service with this record. Look for: An observed feed result is kept separate from the unpowered repair checks. Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R OBSERVATIONS Tool type exactly as printed on the label (required): ____________________ Exact-type manual reference or link that you matched (required): ____________________ Condition found (required): ____________________ Choices: Insufficient line / Crossed or tangled winding / Loose line anchor / Dirty or restricted lever / No clear cause Action completed or linked task still needed (required): ____________________ Result of this task (required): ____________________ Choices: Checks passed; ready for the stated next step / More preparation or a linked task is needed [further care/preparation needed] / Leave unused and contact service [service required] RESULT CHECKS [ ] Sufficient correct line, uncrossed layers and the fig Q anchor have been checked. [ ] The lever is free, the spool is seated and the cap is secure before any retest. NEXT CARE Automatic feed fails or the spool jams Inspect when the stated condition occurs. The manual gives no fixed day or month interval. Basis: manufacturer Source: lst300-manual, English pp10–11 Automatic line feed does not work; figs N, Q, R Record preparation, maintenance readiness, problem located or service needed. This is not proof of a physical repair. SOURCES BLACK+DECKER LST300 instruction manual (manufacturer document, retailer-hosted) https://pdf.lowes.com/productdocuments/1935f26b-7448-4c95-b467-a223bb73d80f/63056925.pdf English pp10–11 Automatic line feed does not work; figs N, Q, R Checked: 2026-10-13 Manufacturer copyright, hosted by Lowe’s. Facts paraphrased; no diagrams or manual redistributed. BLACK+DECKER: locate a manual using model and type number https://support.blackanddecker.com/hc/en-us/articles/360012700118-How-can-I-get-a-parts-list-or-manual-for-my-tool Official model/type lookup instructions; type is beside or below the model number Checked: 2026-10-13 Linked only. BLACK+DECKER LST300 product and support https://www.blackanddecker.com/products/lst300 LST300 model identity; Automatic Feed Spool; Includes AF-100 Checked: 2026-10-13 Linked only; no product photos reused.