I bought a dw511 years ago. Not on Raven. Used in the household for normal drilling and screwdriving, no impact drilling. The armature has a very small diameter worm drive which wears out its teeth and the gear it drives loses teeth as well. New rebar with gear about $60. , not worth repairing. I ordered a replacement Porter cable, it's about 3 inches longer and heavier. I prefer the DeWalt for better feel, the center of gravity is closer to the arm. I can only guess, probably drilled and screwed 2000-4000 screws.