Lifting the cab is easy but that is still a long ways from looking at the chains. remove the two 3/4 inch bolts in the front corners of the cab and lift. Then consult a service manual as you need to remove the plate on the top of the chaincase, brake solenoid, and a bunch of other crap. Have you jacked each wheel up and checked the play in the chains by rocking the wheel back and forth? A couple of inches of play is normal. Drive chains are pretty low maintenance in a Bobcat so your problem may lie elsewhere. I have put thousands of hours on 853's and S185's and never even thought about the chains. Just checked the oil level in the chaincase.