I have a mid 90's 40hp Evinrude Tracker outboard on a pontoon. Last year when I put it in forward the engine popped in an out of gear. So I fixed the problem by adjusting the shift linkage at the engine and now it will go in forward fine but when I put it in reverse it pops in and out of gear. I tried to adjust it many times but could never get it to shift completely into forward and reverse at the same time. What is the cause of this? Any help is appreciated. It is as if the shift lever does not move the shift linkage/arm far enough.