It was converted to a 235 / 12v in the distant past. One might assume the starter is right with the flywheel but who knows? Is there a way to tell?
It works great on some stomps. My guess is that it's sticking intermittently and the gear is not making it all the way to the flywheel. I wondered about linkage, and will study that closer (need a partner), but if it was a linkage issue, why would I hear it spin?