1997 Sea Rayder F16 will not crank

looking for some help. Last week had my jet boat out for the first time this year. It ran ok – a bit of hesitation but figured after sitting for almost a year this would be normal until i ran it for a bit. Anyway took it for a 15 minute ride then back to the dock. 2 hours later it wouldn’t start. After some troubleshooting we assumed it was the starter. I pulled it out and took it for repair. After reinstalling it i had the same issue. the engine will not crank. (i’m assuming now i that actually burned out the starter in the first place). When i say it won’t crank i’m mean that i can’t turn the fly wheel by hand at all. However, if i remove all spark plugs i can turn it about a 3/4 turn one way then 3/4 back. That’s it. It’s almost as if something is preventing it from fully rotating. sorry i should add that I’ve confirmed the battery is good. I also believe the solenoid is good as we were able to bypass it straight to starter and same result. Nothing is sucked up into the shaft. I’m at a loss and was hoping you guys had some ideas on where to start looking. Would a bad impeller jam it up? Thanks for the help !!