I have a customer with an older 543. I had to go to his job site to take a look at it this afternoon. engine starts fine. Bucket goes up, down,and tilts. left side wheels turn as normal. right rear wheel appears to be trying to move but doesn't. Right front wheel turns fine. Now I am an automive tech, not a tractor mechanic, can someone clue me in as to what I should be looking for? If I had a manual this would be easier. Is there a chain adjustment that will hep, or are these rigs purely hydraulic. If it's hydraulic, are the motors hard to replace? The machine is 10 miles from my shop in some guys backyard and cannot be moved. It only spins in circles. I can't even get it on the trailer. Help!