As I've stated here many times, my Alpha One and the shifter do not like rapid shifting between Forward, Neutral and Reverse. With the new slip that I had this season, it caused me to shift quickly to keep control of the boat. It didn't take long for the shifter to start sliding around and not clunking into gear. Since then, I've changed to a new slip that requires much less shifting and so far, it's holding together. But, I feel that I'm very close to losing Reverse. I'm nursing this along as much as possible because if I have to take it to the mechanic, I'll be out of the water for several weeks.
I don't know if your shifter is nearly the same as mine but many times, as i'm moving the shifter, I have to pull the shifter up as I'm moving the shifter forward or reverse or back into neutral. For some reason or another, lifting it a little bit seems to help.