Clean the trimmer housing and vents
Clear accessible grass from air intakes and wipe external plastic while keeping the motor and contacts dry.
Version 2.0.0. Required observations are marked *. Your answers stay in this browser.
1. Match the model and parts
Remove the battery. Find LST300 and the adjacent type number on the tool label. Compare the guard, cap, spool and assembly figures with the linked LST300 manual. Use ServiceNet for your exact type if they differ. LST300 is not a bump-feed head.
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.
Choose the versions you can confirm.
Compare versions →2. Prepare
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.
Consumables and fit
| Item | Specification & fit | Do not substitute |
|---|---|---|
| Plastic-housing cleaner | Mild soap on a damp rag; keep liquid out of the tool External plastic parts only | Immersion, hose, pressure washer; liquid in vents or battery contactsEnglish p10 Maintenance items 1, 3; p3 Safety |
3. Follow your checks
Match the model and preparation to start.
Read all possible routes
Is the battery removed, the trigger released and the cutting head stopped, with no battery damage, exposed wiring or faulty switch?
- Yes — Keep the battery removed for every hands-on step.
- No — 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 — Keep the battery removed. Save your preparation record and check the matching manual before continuing.
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 — Record the label type and matching manual reference in the first step.
- No — 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 — Keep the battery removed. Save your preparation record and check the matching manual before continuing.
Is the dirt accessible on the outside of the tool, with no liquid inside or visible electrical damage?
- Yes — Inspect the intake openings and grip surfaces.
- No — Liquid inside or damaged electrical parts needs service.
- Not sure — Keep the battery removed. Save your preparation record and check the matching manual before continuing.
Can you remove the loose debris without inserting tools into vents or opening the motor housing?
- Yes — Use gentle surface cleaning only.
- No — Leave inaccessible debris for an authorized service center.
- Not sure — Keep the battery removed. Save your preparation record and check the matching manual before continuing.
4. Follow and record
Complete the checks before recording physical work. Follow steps in order.
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.
Manual: Official model/type lookup instructions; type is beside or below the model numberLocate the dirty areas
Set the tool down securely with the guard cutter clear of your hands. Look at the external intake slots, plastic housing and grips. Record whether the slots are covered by grass or only the exterior needs wiping.
Look for: You have identified accessible dirt without removing the housing.
Manual: English p10 Maintenance items 1, 3; p3 SafetyLift away loose grass
Remove loose grass and dirt from the external slots and housing without pushing it inside. Stop if material is tightly bound into the head or cannot be reached safely.
Look for: The visible intake openings are clear rather than packed with debris.
Manual: English p10 Maintenance items 1, 3; p3 SafetyWipe the plastic
Apply mild soap to a lightly damp rag and wipe external plastic surfaces. Keep liquid away from openings and battery contacts. Do not immerse the trimmer, spray it with a hose or use a pressure washer.
Look for: The rag is damp, not dripping; no liquid enters the tool.
Manual: English p10 Maintenance items 1, 3; p3 SafetyCheck grips and drying
Leave the exterior to dry. Inspect the grips for remaining grease, soap or moisture and wipe them clean. The manual specifies dry, clean handles; it does not prescribe a fixed drying duration for this wipe.
Look for: Grips are dry and clean; slots remain visibly unobstructed.
Manual: English p10 Maintenance items 1, 3; p3 SafetyRecord cleaning and the next action
Record the areas cleared and whether the exterior is fully dry. Use the storage task if putting the trimmer away, or the after-care check before normal use. Persistent slow running follows its own troubleshooting task.
Look for: You can distinguish a completed wipe from a remaining operational symptom.
Manual: English p10 Maintenance items 1, 3; p3 Safety
5. Keep your result
Record what you observed. A completed checklist does not certify that equipment is repaired.
When to check again
Grass or dirt on the external air intakes, plastic housing or handles
Keep intakes clear and handles clean and dry; no fixed cleaning interval is stated.
Manufacturer guidance · English p10 Maintenance items 1, 3; p3 SafetySources & fit
- BLACK+DECKER LST300 instruction manual (manufacturer document, retailer-hosted)English p10 Maintenance items 1, 3; p3 Safety · Checked 2026-10-13
- BLACK+DECKER: locate a manual using model and type numberOfficial model/type lookup instructions; type is beside or below the model number · Checked 2026-10-13
- BLACK+DECKER LST300 product and supportLST300 model identity; Automatic Feed Spool; Includes AF-100 · Checked 2026-10-13
Independent, AI-assisted guidance. No physical repair trial is claimed. Manufacturer instructions for your exact version take priority.