El Cheapo rebuilds aren't really fully rebuilt. I strongly suspect that the unit is dismantled, a quick squint at what part actually made it stop worked is carried out. Only the broken part is swapped(and not always with a new part either). So, now it works, but the bearing didn't get changed, the slip rings are still worn, etc, etc. It's just a collection of worn but somewhat functional bits that will fail anytime.

__________________
I choose to be happy, even when the Mercedes is being awkward, lol