If the hydraulics work, and there isn't any active rot, get it.
When you jack it up it may go up crooked or faster in the front,,slower in the rear (or vise versa). Apply some down pressure with your hands to the side that is going up faster as you jack so the tracks dont bind. Once up, be sure to install the cotter pins and release the hydraulic pressure. Chances are the o-rings in each cylinder leak (simple fix), so you dont want to have all the oil leak out and make a mess.
If it doesn't go up, you should be able to squeeze your fingers past the seal between the roof and base to feel for rot under the windows (typical issue).
Another common problem is a rotten floor or one that has fallen apart so the camper flexes side to side. Also check the corners where the eye hooks are located for tethering to the truck. Another spot to check is the bolts that hold the track system to the roof.
I agree with the appraisal of $800-1000 if everything works and no rot (a few stains are OK,,,but no active rot and moisture). That being said, if you find some problems with the hydraulics and cant get the roof up to inspect it,,,you could probably buy that camper for $200-300.
Caution: when jacking be sure the awning windows are closed all the way (you may have to climb inside and latch them as it is going up). The latches can lay open and catch between the top and bottom and bind/bend causing problems.
I also agree that the camper is a mid to late 60's model. It looks very similar to my 1966. The plywood interior on that vintage is beautiful and much stronger than anything they have made since. Alaskan went to panelling in the 70's,,which is garbage compared to the plywood of the 60's.