On one side of the lift arms, there is a rod with a turnbuckle. The turnbuckle is the adjustment.
The adjustment is such that the lift arms should have about 3/4" of "free travel". Meaning, with the lift lever pulled all the way to "up", you should be able to move the lift arms upward another 3/4" by hand, by lifting up on the arms themselves. That is called free play, or free travel.
You'll adjust the feedback rod's turnbuckle until you achieve that free play. Then lock it back down.
It is all in the WSM, as stated....and my 3/4" specification may be off a little...so better check.
What is happening is that either the lift lever is bent slightly, or the linkage has come loose at some point, or perhaps even bent a little. When the lift lever is pulled to "up", the lift arms travel upwards. The feedback rod is telling the position control valve that I'm not to the top yet. The cylinders bottom out, can't travel any further, but since the feedback rod isn't adjusted properly, the position control valve still thinks that it's not up yet...and keeps applying hydraulic pressure to the cylinders trying to lift them up a little further. But they can't so the hydraulic fluid is "dead headed", which puts a big load on the pump, pump driven by the engine, and engine's working harder, which takes power away from, say, a mower or other implement-or the transmission itself.
leaving it like that, where oil is dead-headed, overheats the pump, the fluid, and eventually leads to failure...or in the case of the M8540 I have in the shop, multiple failures.
More specifically the feedback rod and the lift lever need to be synchronized. The lift lever does not have an adjustment externally, so it has to be done with the feedback rod's turnbuckle. If anyone's had the cover off of the top of the transmission and had a looksee underneath it, and how the lift lever is connected to the position control valve, and then how the position control valve is connected to the feedback linkage, it will then become more obvious how it all works in sync with each other.