Before doing any 'bypass' or changing anything (other than getting back to original configuration) you should be able to lift something with the 3pt and gravity should lower it back down. Originally you said it would lift a bale but only about 6" right ? Back then it did lower to the ground when you used the Position Control, right ? If you get it back to that original circumstance, I would try a lighter load on the 3pt (whatever is handy, an implement, a couple guys standing up on the bale forks and holding on, some concrete blocks hung on the bale forks, whatever.) With a load lighter than the bale it should raise way up much more than the 6" and should lower to the ground with that same load.
All the above is correct. Haven't made any 'bypass' as yet, just trying to see if everything is working as it was prior to dismantle. It isn't. Arms go up when the tractor is started and stay up no matter what levers are moved. Fast/slow slide has been moved numerous times with no change is arms position.
There could be something wrong with the lift but I am still doubting it.
Another thought: most tractors have an adjustment knob or lever to control the "down speed" when lowering loads on the 3pt. If that adjustment is jammed at the "slow" setting the lift might refuse to lower or be very sluggish in lowering. I'd play with that control first, move it to the faster lowering position, and see if it will lower normally or not. If it has not been moved in a long time you might want to run that control up and down a few times to free things.