Start by flipping it on its Mag side, checking:
1. Bonded a-arms for any cracks, moisture, corrosion, repairs, de-bonding.
2. Front bulkhead
3. Cracked or kinked tunnel at footrest attach
4. Bent tunnel anywhere.
5. Driveshaft collar and condition.
6. Entire track and skid, skid shocks.
7. Flipping back over, check lower QD sprocket for wobble, looseness, bolt retention, belt condition, belt type (updated or original?).
That's where I would start on a 13 pro. Price goes down if I find issues with any of the above and they were not noted before I got there, and already reflected in a reduced price. All will cost you money to remedy before it hits the snow. Of course, there are many other good items on the list that others will mention. But these are easily missed or hidden problems that are easy to find.