I have two johnson 9.5 motors. The first one is a model # 9R-73B (serial # J3751652) and it will not shift into foreward. I bleieve this motor is a 1973. The second is a Model# MQ-11C (Serial# J2532834)and it seems to cavitate at top end. It will be running along fine and sudenly the propeller seems to stop while the engine continues to run. I believe this one is a 1965 model. These motors appear to be identical under paint and the carbs interchange. Can anyone veirfy the years and help with the problems and or manuals.