New Holland 1720 stuck in 1st gear

[JL628]

I have a New Holland 1720 with the shuttle shift. Always been a great little tractor. TOday I went to use it and it was stuck in 1st gear. (Not the shuttle shifter, the main gear selector to the left of the operators seat) Its always been easy to shift and I use the tractor on a regular basis.
What could be causing this?

 

[Soundguy]

is it 4wd?

if so., drive it fore and back a bit and see if it is driveline wind up.. ( disengage 4wd too.. )

soundguy

 

[JL628]

is it 4wd?

if so., drive it fore and back a bit and see if it is driveline wind up.. ( disengage 4wd too.. )

soundguy

I found the problem, I looked at all the linkages from the side and rear of the tractor. Not until I actually crawled under it could I see there was a little rock stuck between the transmission and linkages, removed it and it works fine now.