Thanks for the post!

If for some reason the components in the hammer drill are not seated properly, it will not hammer. These Bosch units use a special grease. If the grease was low there will be no percussion. The piston acts on the grease which in turn acts on the anvil. If you're mechanically inclined at all I would remove the gearcase cover (where the piston and associated parts are) and make sure enough grease is packed in.

On another note, you could have debris in the collar and in the chuck. Make sure to remove any debris in the collar and chuck and apply the appropriate grease, and after a few cycles you should get the percussion action that you're missing.

You can also see a parts breakdown of this Bosch hammer drill on our site by clicking on the below link:

mastertoolrepair.com/rotary-hammer-parts...hfuoql3fv83vgs5s4577

I hope this helps!