Vermeer 554 xl hydraulic pressure

I try and keep my hydraulic pressure just above green range, in yellow

When I start baling, pressure is set where I want it but an hour or so into baling it climbs to red, last year I got off machine and adjusted it down, back to yellow, and the next day when I would start baking again it would be way low in the green and need to be turned up

This year same thing, it's like it gets hot after an hour or so and pressure goes up? But this year I could barely turn the knob to turn pressure down, couldn't turn it by hand, had to use pliers and was scared it might break it was so tight to turn in either direction

Any ideas? By the way, gauge was replaced 2 years ago, I only do 150 bales a year

Vermeer 554 xl hydraulic pressure