How to Repair Hammering Action in a Hammer Drill

Fix hammer action in a hammer drill

Remove the chuck cover. Pull back the locking bush and remove the rober cup with a small screwdriver

Unscrew the 4 phillips screws and remove the cover

Unscrew the 3 allen screws and remove the metallic plate

Remove the cylinder and find the small piston

The old o-ring

Replace the o-ring with a new one