On my PT425, a pump feeds the steering valve, then the power beyond port on the steering valve feeds the FEL/AUX PTO valve bank. I'm guessing that's what you found.Today, I fixed it!
And made a video.
And ordered a mic, because the one on the GoPro is just miserable!
On the 1850, there is a sticker on the dash that says "Do not use FLOAT while draft control is enabled," which always puzzled me because why would someone do that. And then one day, I was ripping across the field, picked the mower up over a rock and, out of habit, jammed the stick into FLOAT. I found out very quickly that you have no steering when both are enabled....So steering takes priority over FEL/AUX PTO.
If I crank my steering all the way to either side, I sometimes lose FEL function. All I have to do is ease off the steering wheel a tiny bit and FEL function returns.