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OPERATING MANUAL

REPLACEMENT STRING TRIMMER HEAD

MODEL NUMBER AH1520

This Replacement String Trimmer Head is exclusively compatible with  
EGO POWER+ String Trimmer ST1520 and ST1520S.

 

DANGER: 

If the head loosens after it is fixed in position, replace it immediately. Never use a trimmer 

with a loose cutting attachment. Replace a cracked, damaged or worn out cutting head immediately, even 

if damage is limited to superficial cracks. Such attachments may shatter at high speed and cause serious 

injury.

 

WARNING: 

Always remove the battery pack from the product when you are assembling parts, 

making adjustments, cleaning, or when the product is not in use.

1

Fan 

Upper Cover

Washer

Spring

Circlip

Lower Cover Assembly

Cutting Line

Spool Assembly

Nut

REMOVE THE TRIMMER HEAD

1.  Remove the battery pack from the trimmer.

2.  Press the release tabs on the trimmer head and remove the lower cover assembly of the trimmer 

head by pulling it straight out (Fig. 2a & 2b).

3.  Remove the cutting line from the trimmer head.

4.  Take the spring out of the spool assembly, if 

necessary. Save it for reassembly.

5.  Wear gloves. Use one hand to grasp the spool 

assembly to stabilize it, and use the other hand 
to hold an impact wrench (1/2”, 13mm) to 
loosen the nut in a counterclockwise direction 
(Fig. 3).

6.  Remove the nut, washer, spool assembly and upper cover from the motor shaft (Fig. 4).

7.  Use the provided circlip pliers to remove the circlip. Remove the fan assembly (Fig. 5).

INSTALL THE NEW TRIMMER HEAD

1.  Align the key slot in the fan assembly with the spline in motor shaft and mount the fan assembly 

into place (Fig. 6).

2.  Mount the circlip, upper cover, spool assembly, and washer in that order. Use an impact wrench on 

the nut to tighten it.

3.  Insert the spring into the slot in the lower cover assembly (Fig. 7). 

4.  With one hand holding the trimmer, use the other hand to grasp the lower cover assembly and align 

the slots in the lower cover assembly with the release tabs. Press the lower cover assembly until it 
snaps into place, at which time you will hear a distinct click sound (Fig. 8).

LINE REPLACEMENT

 

WARNING: 

Never use metal-reinforced line, wire, or rope, etc. These can break off and become 

dangerous projectiles.

 

WARNING: 

Always use the recommended nylon cutting line with diameter no more than 0.095 

in. (2.4mm). Using line other than that specified may cause the string trimmer to overheat or become 
damaged.
The string trimmer is equipped with an advanced POWERLOAD

TM

 system. The cutting line can be wound 

onto the spool simply by pressing a single button. Loading a full spool can usually be completed in 12 
seconds. 

Avoid repeated operation of the winding system in rapid succession to reduce the 

possibility of motor damage.

1.  Remove the battery pack from the trimmer.

2.  Remove one roll of the cutting line 

(

13 ft.) 

from the package or cut one piece of cutting 
line 13 ft. (4m) long.

3.  Insert the line into the eyelet (Fig. 9) and 

push the line until the end of the line comes 
out of the opposite eyelet.

NOTICE: 

It is not necessary to align the eyelets in 

order to insert the cutting line.

4.  Pull the line from the other side until equal 

lengths of the line appear on both sides of the trimmer head (Fig. 10).

5.  Install the battery pack onto the string trimmer.

6.  Press and hold the line-loading button to start the line-winding motor. The line will be wound into 

the trimmer head continuously (Fig. 11).

7.  Watch the remaining line length carefully. Prepare to release the button as soon as approximately 7 

inches (17.8cm) of line are left on each side. Briefly press the line loading button to adjust the length 
until 5.5 inches (14cm) of the line is showing on each side.

8.  Push down on the trimmer head while pulling on the lines to manually advance the line in order to 

check for proper assembly of the cutting line.

NOTICE: 

In case the line is pulled into the trimmer head by accident, open the head 

and pull the cutting line out from the spool. Follow the above steps to reload the 
cutting line.

Lower Cover 

Assembly

Release Tab

4

Upper Cover

Washer Nut

Spool Assembly

5

Fan Assembly Circlip

6

Key Slot

Spline

Spring

Release 

Tab

Slot 

11

5.5" (14cm)

9

Eyelet

Cutting Line

10

Isometric Cutting Line

3

Impact Wrench

2a

2b

7

8

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