Some maintenance is required, Even if it has oil inside, if you leave it until irs falling apart, it won't be worth fixing. If the tone of your machine changes, inspect it. This Bosch hammer has a bad needle bearing on the crank, a cheap and easy fix. But the customer ran it on until is took out the crank, armature and piston also. Not worth fixing now. #bosch #hammer kango #maintenance #tool #inside #workings #howto #howitworks | Deandohertygreaser