Adjust the auxiliary handle and height

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.

2. Prepare

3. Follow your checks

4. Follow and record

Complete the checks before recording physical work. Follow steps in order.

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.

   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

2. Set a stable starting position

   Support the tool with its cutter clear of you and the battery out. Identify the handle adjustment button shown as 13 in fig H and the height collar shown as 4 in fig I.

   Look for: You can distinguish the handle adjustment button from the two initial-assembly buttons.

   I completed this step and checked the observation.
   Manual: English p8 Attaching the auxiliary handle; figs F–H

3. Choose the handle angle

   Press the handle adjustment button and raise or lower the fitted auxiliary handle. Use the manual working stance as the reference: the front arm should be straight. Release the button so the handle holds.

   Look for: The handle stays at the selected angle once the button is released.

   Handle and height changes made *I completed this step and checked the observation.
   Manual: English p8 Attaching the auxiliary handle; figs F–H

4. Set the shaft length

   Loosen the height collar in the arrow direction shown in fig I. Move the upper housing straight up or down, then turn the collar the opposite way until tight. Keep the normal trimming orientation for this task.

   Look for: The upper housing slides without twisting the tool into edging mode.

   I completed this step and checked the observation.
   Manual: English pp8–9 Height adjustment / Operating the trimmer; figs I, J1

5. Check the working clearance without power

   Hold the battery-removed tool in the stance pictured in fig J1. Set enough height to keep at least 24 inches (609.6 mm) between the guard and your feet; readjust the collar if necessary.

   Look for: The stance is balanced and the documented guard-to-foot clearance is available.

   Handle and height collar both hold their positions *I completed this step and checked the observation.
   Manual: English pp8–9 Height adjustment / Operating the trimmer; figs I, J1

6. Verify both locks and record the fit

   With the controls released, confirm that the handle stays in its angle and the shaft does not slip. Record the adjustment made; a slipping collar or handle is a stop condition. Continue to after-care before use.

   Look for: Both adjustments retain their position without the release being held.

   Result of this task *Choose an observationChecks passed; ready for the stated next stepMore preparation or a linked task is neededLeave unused and contact serviceI completed this step and checked the observation.
   Manual: English pp8–9 Height adjustment / Operating the trimmer; figs I, J1

5. Keep your result

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

When to check again

A different user or an unsuitable working stance requires adjustment

Inspect when the stated condition occurs. The manual gives no fixed day or month interval.

Sources & fit

• BLACK+DECKER LST300 instruction manual (manufacturer document, retailer-hosted)English pp8–9 Height adjustment / Operating the trimmer; figs I, J1 · 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.

Related tasks

• Fit the supplied auxiliary handle
• Set the tool for edging or trimming
• Verify the trimmer after maintenance