i think i broke something (starter won't turn)

Sounds like the solenoid is on it's way out.

Not sure how relevant this is with a bike, but on a boat with a big american V8 we used to have the starter would do nothing every now and then- it seemed to have a dead spot on it, gave it a few bats with an oar, and away it went! Could be when you took the starter off it got it off the dead spot- just a thought!

Yeah it could be that too! I remember having problems with both on my minis. Sometimes it was bridge the solenoid with an allen key and others it was hammering the starter motor. Literally.

hmm, that makes sense. taht commutator thingy inside the motor might have a dodgy segment or two...
well, i'll have to see how it behaves in the future.

thanks for the insights.

Mine did that, it turned out the starter motor had sticky/worn out brushes. I stripped and cleaned the starter motor ans squirted a tiny bit of WD40 on the sides of the brushes.