Check the power feed make sure it works. on The 22-44 (at least mine) there is an adjustment to change the tilt of the column. Make sure it works and that you can get the drum fairly parallel to the table top. Check the gears and how easy the height adjustment works. It should be a bit tight, very little if any slop. Lastly, look at the paper holding mechanisms in the drum to make sure they aren't broken.
Good Luck!
I've enjoyed the Performax 16-32 I purchased last week. All the suggestions above are good. The infeed/outfeed tables are nice! I've used it to flatten 2 cutting boards and some glueups. My 1hp delta DC seems to do a good job handling it. Make sure if they have any extra sandpaper or any other accessories to make sure that they are included. Accessories and paper is pricey. I'm sure you will enjoy it. What model you looking at. I feel that the bigger the better if you have the room.