Originally Posted by tiny
How could gearbox not engage from just sitting under a tarp..
Corrosion of the shift shaft.
Until the mid nineties, Yam shift shafts were made out of steel. They corrode, get thin, start to twist making gear selection difficult and eventually break.
Drop the leg and look up the mid section with a torch. If its broken, bent or corroded, the replacement part is now stainless steel.
Bad news is that normally its powerhead off to change, however, some clever people have managed to modify the head of the shaft.