Stay away from the 75 Hp unless you have a light hull. The 70 hp is a much better all around motor. I also prefer the 86 and later as they are actually prop rated motors.
You need to pull the cover off as the Bendix is under it. The gear spinning freely is normal. The Bendix is attached to that gear also check the Bushing the gear shaft rdes in.
If the head comes off of that motor you can try this. Mix ATF and acetone together in a 50/50 mix and fill the cylinder. Let it sit a week pull the head off and find a Hydraulic press and take your chances.
