Well to actually answer your question, a lot of us are still using BB locos. They are inherently repairable, though parts for the older ones (thinking of the open frame motor era) are scarce. Athearn doesn’t carry parts for them, and the current staff doesn’t have extensive knowledge. (I was told by them.) I had to remotor one of these because the motor was failing.
If you’re planning to convert to DCC, be sure to get a decoder that can handle the current drawn by the older, less efficient motors. Some people remotor these as a matter of course, this gets you lower current drawn, better power output and a physically smaller motor for easier conversion.
For general repairs, YouTube and eBay are useful.