582 Crankshaft will not turn much
I have a 582 that is new to me supposedly with 89 hours on it. The crank shaft will not turn more than a few degrees in either direction with all plugs out and no problems in the gearbox. I have not removed the intake but what I can see of the rotary valve looks normal. The piston tops look normal through the spark plug holes and they are moving in the bores. Can anyone tell me what might be preventing the crankshaft from turning?
Thanks,
Dan