Checking the Auto Trim valve speed

Make sure that any socket is firmly attached. The tool should run at reduced speed.

Set the reversing knob in the reverse direction.
Push the trigger and keep it pressed as you run the tool in the air (A).
Quickly push the reversing knob to the forward direction (B).
The Auto Trim valve shall switch from reduced to full speed.
If the tool is runs with full speed at step 1 (A) or runs at reduced speed at step 3 (B), adjust or service the AutoTrim valve, refer to Adjusting the Switch Point for the Auto Trim valve