What keeps the shift shaft from slipping off of the roller on the shifting drum? While shifting gears the leakage pushes the shift shaft to right causing the shift shaft to come off of the pin on the shifting drum. Then I can not shift at all. Is the leakage suppose to be lined up vertically? I noticed on mine that the linkage from the shift leaver to the shift shaft is at a slight angle, which would explain why it pushes it to the right. Is this correct thinking?

Thanks!

 

Those parts should be aligning at 90 degree angles. A 10mm bolt holding a spring operated "arm" keeps everything in alignment and engaged when you shift. The shift shaft could be bent or maybe something could be assembled incorrect or maybe wore out. You can pull the right side cover off, take the shift components off and pull the shift shaft right out the other side. You may need another push in seal for the that left side cover though.
Gary

 

If you are having problems with the shift lever you may want to get an aftermarket shift lever. They make some that eliminate the linkage and attach directly to the shaft and are much more durable since they're made of thick aluminum. If you have about $70.00 then that might solve your problem, plus I heard that it also shifts more crisply since you get rid of all the play in the linkage. The stock shift lever will bend easily (thankfully it also bends back easily, my 10 year old son bent it trying to repeatedly jam it into 1st gear).

 

The clutch cover keeps the shaft from sliding away.