I'd check for 4 legs, one hole in front to put in wood, one hole in the top to take out smoke, and a door that closes (only on the front, not the top)... Just jokin. You can probably get a sense of how the stove is based on the general condition, after only one season there should be evidence of use, but not trashed. Look for warped metal, cracks in the glass, does the door fit tight, that sort of stuff. You can check anything you want though, but the sellers will probably be your best guide - what are they like? Honest, knowledgeable, etc.? If they bought a nice stove like that new, check with the dealer to see if they'd had any service or warranty problems with it. Not much different than buying a car, you shoudl get a "gut" feeling about the stove and the sellers. We saw one in the stove shop and loved it; we've orderded the T6 but if there'd been a used T5 available it might be in our living room right now...! Good luck and enjoy if you get it. FYI our stove shop's selling theirs for $1740 plus tax, but it's a demo model. Not sure how that compares to the one you're looking at but you can ask chimneysweeponline or another dealer for a ballpark of what's reasonable.