One thing I would suggest is to just clean all of the contacts, the contacts for the brushes, the switch contacts, etc.
Many times I have had something not work at all due to a dirty contact, especially if it is in a dusty environment. It might save you some money.
I don't know which contacts are sealed, and which ones are exposed, but it is worth a try.
There is my 2 cents worth!
If you live to love, then you'll love to live!