A couple of years ago mine got balky going into first gear. All that was needed was the two dollar bushing on the shift lever end of the 1-2 shift rod.
All the other bushings were okay. The dealer even had the bushing in stock as it is apparently the same one used for autos, and it's a common replacement item.

Inspect all the bushings on the linkage, renew them as required, and go from there.

Duke