I recently purchased an older used DW059 (has base for ni-cad I'm using xrp lithium). Worked OK then was down on power. Took it apart and found it needed a brush and the fan shroud was broken. Replaced those two parts, seems to work. My last impact was a 20v Craftsman Pro and it was badass. This thing is pretty sad. It has trouble with car lug nuts. Is this just how they are or is mine messed up? Any way to test it?