O-RING 1610210187

1. Removed and cleaned old grease off all parts
2. Replaced the piston o-ring and re greased everything
3. Noticed the hammer pin seemed tight so greased and loosened it.
4. Put it all back together and it works much better. I think the final hammer pin was the biggest problem since no grease was used when installing bi ... Read more ts previously.

1. Pry off the rubber end with a flathead screwdriver.
2.remove the retaining ring. You can do it with some finesse and screwdrivers. Then remove the bit holder assembly. (Spring, ball, washer, etc )
3. Remove the selector switch. Do this by pushing in the red button and turning it beyond the hammer position, then pull out wit ... Read more h pliers.
4. Use torx head screwdriver (t-20?)to remove the front housing bolts, then remove housing .
5. Now you\'ll see the piston/cylinder assembly. Grab the tip of the piston with needle nose pliers and pull it straight up and out of the cylinder.
6.use a pick tool and remove the old o-ring.
7. Grease up the inside of the cylinder and the piston and install the new o-ring onto the piston. Insert the piston into the cylinder.
8. Now is a good time to clean and regrease everything.
9.put the front housing back on and tighten the bolts.
10. Put the bit holder assy back together.
11.put retaining ring back on. A spark plug socket will help, then two screwdrivers. Put rubber top back on.
12. Put selector switch on.

I think that\'s all that there was to it. If I forgot a step or two, you\'ll figure it out. Good luck.