Welcome to TBN, Joe!
Have you ever had the PTO engaged before, or did you just get this tractor? If you have used the PTO before, how long ago was that?
joesaladino said:
I took the plate off that contains the lever
By "contains", do you mean that the cover contains the pivot point for the lever? If so, I assume the lever moves freely at that pivot point.
Through some linkage, your PTO lever is connected to a fork which fits across the gear which engages your PTO. Somewhere in that linkage there is almost certainly a spring-loaded ball bearing. The spring pushes the ball bearing against a shaft that has two detentes (depressions) in it. One detente is for "not engaged", and the other for "engaged". When the lever is in the right position for "not engaged" or "engaged", the ball drops into the detente and keeps the lever in that position.
After years of wear and tear,
the spring loaded ball bearing might be binding in the detente. Typically the edges of the detente wear and may have a burr, or the clearance between the shaft with the detente and the sliding part containing the spring loaded ball bearing gets too great. The ball bearing could also be worn to a non-spherical shape.
This doesn't sound very professional, but sometimes if you wiggle the lever around a lot while trying to shift it, you'll get lucky and the ball will slip out of the detente.
Find the part inside the casing which the lever connects to and see if you can slide it. If you can't move it by hand, try wiggling it around or perhaps giving it a light rap with a hammer. That won't solve your problem, but it might help you identify what the problem is.