Hmmm....... This isn't rocket science......
Here's a old post, This is what your dealer's should have done;
Originally Posted by Restrorob
First check ALL tire pressures then the hydro belt for looseness/wear, Check the dump valves for being closed all the way. Then all linkage for wear/slop including the lever on the pump shaft. Check all hydro hose fittings for being tight, One could be sucking air but not leak oil.
If all the above checked OK, They should have adjusted tracking. If tracking can't be adjusted so the unit goes a straight line, A flow meter test should have been performed on the slower (Left) side to determine which is faulty, The pump or motor.
Nearly anything can be repaired, One must have the knowledge and proper tools along with the will power to do so.
Yes, I'm a Dixie Tech here in Florida and there's NO doubt in my mind I couldn't find your issue in less than half hour.
Print this post out and take it too them, Maybe they'll learn something.......