It could be a Quadra or Mag fork, I'm leaning towards Quadra 10. Looks like the stanchions are in the up position. You can pull up the boots and see if there are obvious signs of corrosion by the lower seals, but most likely the stiction is happening inside the lower legs. It's either corrosion or elastomers gone hard over time. Either way, the fix is to take the fork apart and replace the internals, and chances are you won't be able to source replacements. I would recommend not sinking any time or money into it. It's a threaded fork but if it has a 1 1/8" steerer you can replace it with a different 26" fork with cantilever posts, and maybe take the opportunity to switch to a threadless headset as well.

The knobs at the top are to adjust compression. If it's a Mag, then it'll be an air fork, and one (or both) knobs can be removed to reveal a Schrader valve or needle port (like on a basketball) for inflation/tuning. I don't think those forks had any rebound adjustment.

Edit: looks more like a Quadra than a Mag. Definitely not a Judy due to the lowers. It should be pretty easy to take apart, but there still may not be an easy fix.