[rotorwrench]

If it's stiff to move the shifter with engine running while the gearbox is in neutral with clutch completely disengaged, then I'd pull the shift tower off and check the 1st/reverse shift fork shaft and fork for damage or stiffness in movement. If the shifter function is normal & the fork is straight and in good condition, then a person will have to see if the 1st/reverse gear is hard to slide on the main shaft. There could also be a problem with the reverse idler gear down in the lower part of the case but that would only affect the reverse mesh for the most part.

All of this hinges around whether the clutch is completely disengaging as was mentioned before. The clutch has to completely disengage or the input shaft and counter shaft will still be turning to some degree.

See if the transmission is full of the recommended gear lube as well. It has to have that lube in there to slow and stop the counter shaft cluster gear.