Set the tool for edging or trimming
Rotate the lower housing through the documented half-turn and set the wire guide with the battery removed.
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
No replacement consumable is required for this check. Damaged parts need an exact-type match through manufacturer support.
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.
Do the collar and wire edge guide match figs I and K–L and appear undamaged?
- Yes — Confirm the current mode before releasing the collar.
- No — A different guide or adjustment mechanism needs its own type manual.
- Not sure — Keep the battery removed. Save your preparation record and check the matching manual before continuing.
Can the collar be released and retightened normally, with the shaft and housing supported?
- Yes — Make the mode change with no battery installed.
- No — A slipping collar or binding adjustment needs service.
- 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 numberIdentify the current mode
Keep the battery removed and compare the current head orientation with the normal trimming view and edging view in figs J and K. Record which mode you need next.
Look for: The desired change is clear before you loosen anything.
Manual: English p9 Convert to edging mode; figs I, K–LRelease the mode collar
Support the tool and turn the collar in the release direction shown in fig I. Hold the metal shaft so the adjustment is controlled; keep the guard cutter away from you.
Look for: The collar releases without force and the metal shaft remains supported.
Manual: English p9 Convert to edging mode; figs I, K–LRotate the lower housing
For edging, hold the metal shaft and rotate the lower housing 180 degrees into the position in fig K. To return from edging to trimming, rotate it back 180 degrees to the trimming position.
Look for: The head orientation matches the selected figure; this is one half-turn, not a shaft-height adjustment.
Manual: English p9 Convert to edging mode; figs I, K–LTighten and position the wire guide
Turn the collar back until tight. For edging, position the tool with the wire guide along the working surface as fig L shows. For trimming, retract the guide to its original out-of-the-way position.
Look for: The collar is tight and the wire guide matches the selected mode.
Manual: English p9 Convert to edging mode; figs I, K–LCheck the selected setup without power
Confirm the collar holds the head orientation and the guard remains secure. Record the chosen mode. Before any use, finish after-care; edging requires at least 100 feet (30 m) between the work and other people or pets.
Look for: The mode is mechanically set; no powered cutting is part of this adjustment task.
Manual: English p9 Convert to edging mode; figs I, K–L
5. Keep your result
Record what you observed. A completed checklist does not certify that equipment is repaired.
When to check again
Changing between normal trimming and maintenance edging
Inspect when the stated condition occurs. The manual gives no fixed day or month interval.
Manufacturer guidance · English p9 Convert to edging mode; figs I, K–LSources & fit
- BLACK+DECKER LST300 instruction manual (manufacturer document, retailer-hosted)English p9 Convert to edging mode; figs I, K–L · 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.