Whats wrong with it?? We had starters for the Johnson 70's a few years ago and got them reconditioned. I cant remember where, but new bushes etc put in and away we went, for a lot less than a new one. Talk to auto electrical places, they could help.
Spoke to my old man and he still has a old starter from one of his 85's, but it is in pieces and he says that he does not really want to part with it. He recons that they are quite hard to come by...... sorry man, but i will ask around for you, have a few friends in the Snoek fishing industry and the smaller boats all use 85 Yammies, has to be one of the best engines that Yamaha ever made!!