Check a spool cap that will not latch ID: lst300-cap-latch 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 [ ] Material: No replacement material needed for an intact tool 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 Replacement spool cap: BLACK+DECKER RC-100, confirmed against the exact tool-type parts list Fit: Original compatible AF-100 housing with undamaged slots Do not substitute: Damaged housing; caps with different tabs; forcing an apparently similar part Source: lst300-manual, English p9 Cutting line / Line feeding; Replacement accessories 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: Do the cap and housing match the exact-type manual and RC-100 specification? Yes -> check-2: Check the two retaining sides separately. No -> prepared: Identify the correct cap before trying to fit it. Not sure -> prepared: Keep the battery removed. Save your preparation record and check the matching manual before continuing. check-2: Are both cap tabs and housing slots intact, without cracks or distorted plastic? Yes -> steps: A seating problem may be corrected by cleaning and alignment. No -> service: Broken retention parts need the correctly matched replacement or service; do not tape the cap down. 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. Inspect both retention points Remove the cap by pressing its tabs. Compare each tab and each housing slot with fig O. Note trapped grass, a line caught under the cap, or a spool sitting high; do not bend the tabs. Look for: Each retaining point is intact and the obstruction, if any, is visible. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O [ ] 3. Clear the slots and rim Remove loose dirt and grass from the housing rim and slots. Keep the feed lever in place. If the lever is displaced and its fig N position is unclear, stop before refitting the spool. Look for: The cap seating surfaces are clear and the lever position is known. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O [ ] 4. Correct the spool and line position Guide the single line through the eyelet. Set the original compatible spool on the boss and rotate it slightly until fully seated. Move any line away from the cap rim. Look for: The spool rests fully down and no nylon crosses the cap seating surface. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O [ ] 5. Align and snap the cap Match both tabs with their slots and press the cap onto the housing until it snaps securely into place. Do not try to overcome resistance by striking the cap. Look for: Both tabs engage; a click on only one side is insufficient. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O [ ] 6. Check retention and record the result Gently check that the cap remains attached without holding its tabs in. Record whether cleaning or seating resolved the problem. If it still will not retain, keep the battery out and obtain service or a confirmed compatible cap. Look for: The cap stays retained on both sides, or the tool is clearly left out of use. Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O OBSERVATIONS Tool type exactly as printed on the label (required): ____________________ Exact-type manual reference or link that you matched (required): ____________________ What prevented the cap from seating? (required): ____________________ Choices: Loose grass or dirt / Line trapped at the rim / Spool sitting high / No clear cause Both tabs now hold the cap securely (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 [ ] Both tabs and slots are intact, clean and aligned. [ ] The spool is seated with an unobstructed eyelet path and the cap holds without force. NEXT CARE Cap will not snap securely or was removed for line care Inspect when the stated condition occurs. The manual gives no fixed day or month interval. Basis: manufacturer Source: lst300-manual, English pp9–10 Replacing the spool; figs M–O 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 pp9–10 Replacing the spool; figs M–O 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.