Might be fork wear? Is it all gears, or just ones on the same side (1 & 2 on one fork, 3 & 4 on another, 5 & r on third)?
Pull the drain plug and look for bronze in the
oil.
Check out your parts manual and service manual here:
http://www.ttcautomotive.com/English...ts/TR-3550.asp
If it comes down to it, can you pull the top plate off the shifter to view the shift rails?