I am having the same issue except with a stock bendix, and an after market ebay cheapy starter. the starter has a whine to it even without the bendix attached. I am going to rebuild my stock starter and see what the deal is.

 

I have had very bad luck with the bendix's that were purchased off e-bay.They spin and do not engage..Put a stock one in from Polaris and it worked fine..I guess you get what you pay for...............

 

Does the bendix not engage at all or does it catch sometimes. I bought one of the ebay bendix thinking that it was the issue but it did the same thing. Some times it would grab but not enough to start it

It ended up being the spacer that the ends of the bendix sits in, these are round and it was ovaled out. I replaced the spacers and the ebay bendix worked perfect. It is probably going on 2 years now.