Welcome to the forums. Do you ride in a lot of mud and water? If you do, maybe they're getting mud and water in them. I know they're sealed, but I have took some apart that have been full of mud.
Yeah, possibly.i'll tell you something else it could be too..the one way bearing may be hanging..draging the starter.which..in turn..over heats it ??..just a thought.I fixed a 660 Raptor a while back that wouldn't turn over with a new battery and a good starter and that was what was wrong with it. It would turn over sometimes and sometimes it wouldn't, mostly it wouldn't. The Rubicon is a little smaller engine, so it may turn over, but just put a lot of extra strain on the starter.