Check everything you can. You have a pretty good list but check for leaking/weeping cylinders, pumps etc. Look at the fluids, oils with water in them look like a creamy coffee color etc. Check the coolant for level and color. Smell the oils, look for a burnt odor etc.
I also look for a machine which needs some repair which I can do myself and parts/supplies are relatively inexpensive. I stay away from machines which need repairs either I am not equipped or prepared to do or else parts/supplies are very expensive. For instance a machine which needs welding repairs, paint etc. which I can do myself I look favorably on. A machine which needs expensive parts such as hydraulic pumps/motors, undercarriage on track machines, large qty or size of tires or a new engine/transmission etc I would tend to steer clear of. Don't expect to find a machine in perfect condition at a bargain price, seldom happens.
No auctions I've attended would allow you to pull injectors on a machine to test compression. You pretty well have to do your assessment visually or a brief start up and testing the control functions. No actual operating allowed.
Unless you are very confident in your skills bring a mechanic friend with you, he might spot something you might miss.
Talk to other bidders at the sale but beware, they may give negative false info if they wan't to discourage other bidders on a machine they want or may be shilling for their own equipment to get a higher price.
Skid steer loaders and 1 ton dump trucks are common on kijiji/craigslist etc. A local seller may allow mechanical inspections, test drives, machine operation etc. and more time to check out what you are looking at. Usually you can come to a mutually agreeable price conditional upon inspection or test operation, the seller may also deliver the machine free or at lower cost to help make the sale. I would look for the equipment you are seeking here if you have enough time for the right machine to come along.
Good luck whatever you do, let us know here how you make out.
