It's been a whole day and you've had no replies.
We're not ignoring you, probably most folks, like me, don't have an answer for you.
I had a 3600 with the same problem. I never did fix it. Just used position control for the summer I owned the tractor and then sold it that fall.
I doubt it would be hard to fix. You will need to pull the lift cover and have a look see. Pulling the lift cover is no big deal but it's heavy so it helps to have a helper or a cherry picker to pull it. That draft handle is infrequently used so i suspect it's just dry and froze up for lack of lube. Do a bit of sleuthing. I'm sure you'll find the problem. Please post back with your results.
We are all learning here.
A top cover gasket should be available from this site but unfortunately I'm not finding it for you. Your local CNH dealer should have one in stock. You will need one so order it before you start.
Click on the link below for a diagram on that top cover. That is an outstanding small tractor.