If the lever raises, the implement will follow and raise also. I don't have a WD or WD-45 in front of me so I am going totally by memory. The IT manual gives no help. I know of nothing in the system that would cause this lever to move unassisted. There is linkage for the lever and sometimes the hoses can interfere with the motion of the levers. So I'd check that first. I don't think there should be any extension springs on the linkage. If there are, remove them and see if the problem is fixed.
This seems like a very baffling problem. Hope someone else can help.
Additional info might help. Did you just buy the tractor? If not, is this a new problem?