No, that damper definitely can't be rebuilt. Do you agree that it's shot based on the video of it being pushed down but not returning on it's own?
Its looks like its junk how much is a new one ?
That was my thought too. It's about $100. The original issue I'm trying to solve is the pedal not returning to center - the machine creeps when you step off the pedal. The centering damper seems to work fine; has good return rate, etc., and it's not an adjustment issue (you can adjust where the centering point is). And, I see his other damper looks like toast and am hoping that is the issue. But, I have to say, I don't quite see the relationship of how this damper influences the pedal return. I guess the pedal must need a certain amount of force from that damper, and without it the pedal somehow doesn't snap to center properly.
The damper is there so the pedals return to neutral gradually when you take your foot off. Otherwise the tractor slams to a stop like mine does. I have to let off the pedal a bit gradually.
The gas is in the damper to account for the space the rod takes up when the piston is fully seated. Some dampers just have atmospheric pressure air. There are reasons why that's not optimal in vehicle suspension but that's not relevant here.
If it is a gas pressure damper, and from the screw on the side that looks like a gas port it looks like it might be, then the other spring might be there to counteract the gas pressure. If the gas pressure is gone then the spring would be pushing the pedals past the neutral point. If it's easy to remove the spring you could try running it without to test this theory.
If there's a gas port the damper is might be rebuildable. Suspension rebuilders have equipment to put new nitrogen in shocks. But a rebuild would probably cost you about as much as the $100 for a new one.
The one with the screw on the side is the centering damper. That one certainly controls the speed of the return and centering between fwd/reverse. But this is not the damper with the issue. The one that seems to have an issue is the one that looks like a little gas strut. I believe it's the combination of this gas strut and the centering damper which returns the pedal to neutral gradually when you take your foot off. With both disconnected and the engine off, the pedal just flops back and forth with no resistance (not sure if this changes when engine is running). At any rate, it seems the gas strut is toast per this video: