When it does this, will the 3pt still raise/lower? Does pto still spin? Power steering still working? Does it make any difference if you shift the range selector? Any odd noises when it acts up?
Just making a guess that there is something external to the transmission -a shift linkage, a sensor or switch as mentioned, etc. that's either bad or misaligned.
Just making a guess that there is something external to the transmission -a shift linkage, a sensor or switch as mentioned, etc. that's either bad or misaligned.