We had that problem once on a TR85. We ended up taking off the ring that holds the turrent in place, and cleaned out all the built up gunk. After we cleaned it and greased the snot out of it, it worked like it should.
We had trouble where it had worn through in the tank where the turret is and that let a bunch of junk in the ring. Thats something to check as well. Might need to do some patch to keep stuff out of there.
The ring can be cleaned and rotated a quarter turn or so to help. also check the bolts in the hyd. cylinder mounting bracket. they are sloted and if loose can make it hard or impossible for the cylinder to move the auger in or out.