Engine may have set for months before I bught it. Can be easily tunned by had by rotating flywheel, indicating compression prob and stuck rings? In BAJA - hard to find compression gauge. Your thought on freeing rings?
I can easily turn my 1988 140 looper by hand. That doesn't tell you anything with a two-stroke engine. If you have stuck rings, usually a thorough decarb will free them if they are not rusted.
Is this motor the 50 HP One? There are no 84HP models.