Divide and conquer is definitely the way to go. You have eliminated the control box and cables as your main problem. MY next step would be to pull the shift cover off the exhaust housing and grab hold of the shift rod and/or connector….maybe with needle nose vise grips….and try to limit up and down motion of the shift rods, while trying to move the shift lever back and forth. You would be checking for excessive lost motion in the linkage under the power head. I used to see some bad wear up there, sometimes. IF that checks out okay, loosen up the shift handle on the horizontal shift shaft, so it is free to move within its adjustment range. Don calls this “the fine adjustment.” Now, move the shift rod up and down, through full engagement, forward and reverse, and see if that adjustment is always within an obtainable place. (Now you’d be checking for excessive lost motion in the gear case.) I’m not sure how to better explain that. What I am trying to say is that if shift rod travels up and down more than the shift handle and shaft can travel, then you have a gear case problem, in my opinion. You might find a bent or worn shift fork, wrong size clevis pin, (I have seen it) etc. You may also have a worn out FORWARD gear, and someone over-adjusted the fine adjustment, to over-compensate for it, which leaves you short on travel in reverse.
Long live American manufacturing!
