Fit the supplied auxiliary handle

BLACK+DECKER LST300 · US · AF-100 · Maintenance

Match the grooved handle and housing button, attach the original handle and verify its snap fit before adjusting the stance.

Version 2.0.0. Required observations are marked *. Your answers stay in this browser.

Two-button release, grooved alignment and full handle snap fit. Original guide illustration; compare the parts with your manual.

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.

Model and tool typeRemove 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 headDo not substitute a bump-feed procedure, dual-line spool or metal cutting attachment.

Choose the versions you can confirm.

I compared the label, manual and parts with this guide.Compare versions →

2. Prepare

Stop and get help

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.

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 lightingMaterial: Original supplied undamaged auxiliary handle

Consumables and fit

Item	Specification & fit	Do not substitute
Auxiliary handle if a replacement is needed	Exact LST300 tool-type part from manufacturer support Original documented groove and two-button mounting	Unverified handle, altered grooves, broken housing buttonsEnglish p8 Attaching the auxiliary handle; figs F–H

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 this the original supplied handle for initial assembly, with the grooved attachment shown in figs F–H?

Yes — Use the assembly buttons on both sides of the upper housing.
No — For an already fitted handle use the adjustment task. Different or damaged handles require exact-type support.
Not sure — Keep the battery removed. Save your preparation record and check the matching manual before continuing.

Are both housing buttons and the handle attachment points intact?

Yes — Align the matching grooved surfaces before pressing the handle on.
No — Do not attach a handle to broken or damaged supports.
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.
Tool type exactly as printed on the label *Exact-type manual reference or link that you matched *I completed this step and checked the observation.
Manual: Official model/type lookup instructions; type is beside or below the model number
Identify the assembly features
With the tool supported and battery removed, identify the two upper-housing buttons marked 12 in fig F. Compare the grooved handle side with the grooved housing button in fig G.
Look for: The matching grooved sides and both assembly buttons are identifiable.
Supplied handle and groove match checked *I completed this step and checked the observation.
Manual: English p8 Attaching the auxiliary handle; figs F–H
Press the two housing buttons
Press the buttons on both sides of the upper housing as fig F shows. Keep the handle in the orientation pictured in fig G; avoid trapping fingers between the handle and housing.
Look for: Both buttons are depressed and the handle approaches in its matching orientation.
I completed this step and checked the observation.
Manual: English p8 Attaching the auxiliary handle; figs F–H
Start the handle on the matching grooves
Partially push the handle onto the housing, matching its grooved side to the grooved button. This initial position should hold the buttons in when your hand releases them, as the manual describes.
Look for: The partly fitted handle holds the buttons in without being forced across the grooves.
I completed this step and checked the observation.
Manual: English p8 Attaching the auxiliary handle; figs F–H
Complete the snap fit
Push the handle fully onto the housing and adjust its position slightly until it snaps into place as fig H shows. If it resists or fails to engage, stop and recheck the matching parts; do not strike or modify them.
Look for: The handle is fully attached and remains held when released.
Handle snapped fully into place and stays attached *I completed this step and checked the observation.
Manual: English p8 Attaching the auxiliary handle; figs F–H
Check attachment and plan adjustment
Check that the handle stays attached. Use its adjustment button to select an angle, then follow the handle-and-height task for the full working stance. Record the fitting result and keep the battery out until after-care.
Look for: The original handle is retained; height and stance are checked in the linked adjustment task.
Result of this task *I completed this step and checked the observation.
Manual: English p8 Attaching the auxiliary handle; figs F–H

5. Keep your result

Grooved handle and button are correctly matched and the handle is fully snapped onto the housing.The attached handle remains secure before height adjustment or normal use.

Record what you observed. A completed checklist does not certify that equipment is repaired.

When to check again

Initial assembly of the original supplied auxiliary handle

Fit during initial assembly; use the separate adjustment task when changing the working stance.

Manufacturer guidance · English p8 Attaching the auxiliary handle; figs F–H

Sources & fit

BLACK+DECKER LST300 instruction manual (manufacturer document, retailer-hosted)English p8 Attaching the auxiliary handle; figs F–H · 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.

Fit the supplied auxiliary handle

1. Match the model and parts

2. Prepare

3. Follow your checks

Is the battery removed, the trigger released and the cutting head stopped, with no battery damage, exposed wiring or faulty switch?

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?

Is this the original supplied handle for initial assembly, with the grooved attachment shown in figs F–H?

Are both housing buttons and the handle attachment points intact?

4. Follow and record

Record the exact tool and make it safe

Identify the assembly features

Press the two housing buttons

Start the handle on the matching grooves

Complete the snap fit

Check attachment and plan adjustment

5. Keep your result

When to check again

Sources & fit

Related tasks