my advise would be to take someone who has operated and or worked on heavy equipment ,there is so much to be looked at if you have no idea . If that is not possible first case equipment is a quality machine. And check all the fluids and make sure that there is no water in fuel and oils, look at the filters and see if they are dates written on canisters that might give you a idea of how it was serviced, look at the joints and see if there is fresh and old grease at the pivot points that is a good thing no grease can possibly be a problem. Look at where the machine is parked look for oil spots on the ground. Of course run the engine and look for blow by . And before that I would make sure the engine is cold and then start it if you need starting fluid to get it to go, not good. And operate it as best as you can to see if there is any glaring problems with the drive , good luck
