Never dealt with that baler, but checking the belt condition is a good start. Check belt lacings to see if they look like they are going to pull out also. Also check condition of chains and sprockets. If at all possible the baler should be hooked to a tractor so you can hear it run, when I bought my present baler it had a bad bearing which made a terrible knock. (dealer took care of it) With the baler running you can check to see if any shafts are running crooked and that no sprockets are warped. Raise tailgate and see if it leaks down.