The 460s particularly the early ones use the same type of PTO that the early 560, 450, 400, MTA, 300, and 350 used. Basically the unit is driven all the time straight off the engine, but it gets it's gear reduction from a planetary setup not that dissimilar from the TA setup. Lets go through this real quick, I'm going to be referencing the image below as far as numbers go.
Long story short the power comes into the unit from the input shaft (18 + 19) straight off the engine. It is then sent to what I call the sun gear (8) which spins at engine speed. From there there is a planetary setup on the output shaft (6) which provides a speed reduction and torque multiplication. Well, that's all fine and dandy, but how do you shut this thing off? Well, there are two bands (clutches or brakes) that direct which way the power is diverted. Lets talk about what's going on when you want the PTO off.
The first band/drum setup I'm going to talk about is (34 the band and the rear most drum is 38 ) 38 is keyed and slips over the top of the output shaft and it's keyway (5 + 6). So when you want the PTO to stop the band (34) is clamped down on that drum via your hand lever. Next the idler drum (35) also has a band on it (34) and it is released to spin freely to redirect the rotational energy. Idler gear (36) is fastened to drum (35) and the rotational energy is transferred from the sun gear and planetary gears to that idler gear (36) which slides inside the output shaft and also acts as an idler to help keep the planetary gears in place. It's pretty simple once you figure it out in your head.
And the opposite happens when you want the PTO to spin. So what you have happening here is drum (35) is locked up tight on it's band and 38 isn't grabbing at all. So one of three things is causing this if you have this style of PTO.
1. Bands are badly worn and need replaced.
2. Bands are badly out of adjustment.
3. Something broke IE the keyway inside the PTO.
Get a manual and adjust it accordingly, but it sounds like something is amiss. It's not uncommon for farmers in a pinch when a PTO starts to slip to swap those bands around to buy them some time and to get the tractor back out in the field, but what happens is this temporary fix became a permanent solution for the farmer. Thus, what you run into later down the road is problems with the PTO not disengaging, which is what you have. Probably would be best for you to tell us which PTO you have though because the two are different.
