well its good you found the fuse blowing problem, a co-incidental other problem that came up, those can always be confusing when you are trying to relate it to what the lift was last doing when the fault occured.

I do want to make you aware that stalling these lifts can also create new problems that may not be apparent at the time but will come up later on after continued use. Yale makes some pretty tough motors but even they are not impervious to bad driving practices like stalling the system out. One of the most common occurances that comes up during a stall condition is the com bars in the motor will heat up and raise up, this will create an uneven surface on the commontator of the armature and end up creating an intermittant drive error problem with the drive later on because the brushes will jump off of the commontator during driving opening up the drive circuit long enough to trigger the drive error code. This condition is generally identified early on from a clicking sound you hear while the lift is being driven in fwd or rev. If you begin to hear this at any time you know then that this problem is there.
Unfortunatly there is no good fix for this other than resurfacing the com bars with a seating stone OR pulling the motor out and having the armature cut back smooth, or a more permanent fix would be to just replace the armature which is very expensive.

So if you start hearing this clicking sound coming from the drive motor be prepared to deal with it because it will not just go away, even after using seating brushes it will still occur, once the com bars are heated up and come loose they never go back and will continue to come out during use.
Just FYI....

Check the voltage and polarity on wire 6 and wire 8 at the control card.

Well found it, apparently at one time it had a backup alarm, which was only partially removed, they left the alarm input wire from the rev contactor coil hanging in the breeze because it was tucked up behind everything and not easily accessed. Grrrrr.

My biggest problem is the dwgs don't use std symbols, and there's no legend to define their terminology. A coil or solenoid is a coil or solenoid and should always be drawn that way, not with these guys, you need a secret decoder ring to figure out the non-symbol symbols.

That's kind of a strange problem. I would look in the forward and reverse lever switch to see if anything is broken and shorting. Those switches also have a separate circuit to turn on the steering. If the switch broke internally and shorted it may cause a problem. Also I think there are diodes in that switch housing that are in the hour meter circuit that may cause a problem if they have a short. If there are diodes try disconnecting them and see if the fuse still blows. You can also test the circuits in the reverse switch. I think there are 3 separate circuits.

Yup, msg #1.

Does the power steering turn on ok when you put it in forward?

Yup. No throttle, soon as you switch it to rev pops the fuse. There is no backup alarm.

Happened after he got it stuck and really hammered on it in rev.

Pump motors are functional, mast controls are normal, fwd is normal.

It blows the fuse without touching the throttle petal? Back up alarm?