I got a pack of 10 micro stepper motors off ebay a while back, they were surplus camera focus motors.
Eventually I had a use for one, in a aircraft instrument I'm adapting, so I pulled one out wired it up to a microcontroller running a microstep routine, worked fine, pulled another out, dead and another dead, and another dead, 3 out of the 10 work.
I'm getting open circuit on one of the wingdings, not always the same one.
So I'm thinking that these were probably a scrapped batch that fell into the wrong hands and ended up on ebay.
I'll dissect one and see where the issue is, it might just be a naff job cleaning the enamel off the copper where the leadout is soldered.
Edit: I forgot I had a pocket microscope, using it you can see it looks as though the enamel wasnt scraped off at all, so either its that weird stuff that solders through or they forgot to do it.