I've got an Onan 5BGE and I think the starter is out, it just makes an awful grinding sound when trying to start. Engine is not frozen up as I can turn it over with an allen wrench.
I've tried to remove the starter and got the top bolt out and found out that it has a captured nut on the backside that fell out when I removed the bolt. I can get to the bottom bolt with a socket and extension but I can't reach the bottom nut on the back side to replace it when it would fall out.
I don't have the resources to remove the generator itself sitting in my driveway so unless I find a way to get to that lower nut, I'll have to take it into the Onan dealer.
1996 Itasca Suncruiser 34RQ, P32 w/ 454 TBI, Banks Air Intake, Harris Towmaster Performance Chip pulling a 2012 Jeep Wrangler Unlimited.