On the locking collar issue, I believe the manual is correct (imagine that). Lock the collar counterclockwise standing in front of the engine facing the PTO. This is necessary because resistance to the engine's rotation (caused by a load on the belt) creates a clockwise torque, effectively tightening the collar.
All of the PTOs I've removed save one were properly installed, one had to be loosened counter clockwise but most had to be untightened clockwise. To be honest, it's all a little theoretical because if the collar is tightened robustly with a punch and a hammer, it's unlikely to loosen either way.
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