I've been using a Porter Cable model 7750 2 speed variable speed hammer drill alot recently. I was working fine drilling 1 inch holes in concrete until yesterday. First I noticed that it wouldn't run until I hit the starting trigger two or three times. Then I noticed it was slowing down and almost stopping while drilling. This is a very strong drill and I have drilled 9 12 inch deep holes without it slowing down once so I know there is something wrong. It's running too slowly now to be useful, and the shaft is turning freely and I don't feel any unusual play in the shaft.
The only thing I can think of right away is that the brushes may be worn out. Do these symptoms sound like that? Looking at the drill I don't see an obvious place where the brushes could be changed.
If anyone has had similiar experiences with a drill please let me know how you resolved it.
Thanks,
John