Tom Gardner Mars@Tacks fired this volley in
:

I have a "Servo Products" power feed that pops it's internal breaker as
soon as the power switch is turned on. The only thing I've checked so
far is the brushes and they are fine. Any direction?

It might have a shorted direction switch, causing a dead-short on the
incoming power. It might have a shorted winding. In that case, you're
screwed.

I've got a $300 Chinese cheapy as the knee drive on my R2E4, and it's
been in service for - what? - over ten years(?) on two different
machines.

Lloyd