2014 T7 70 2600 charged pressure low after warm-up

Need some help with the proper testing procedure to rule out what’s good and bad
2014 t770 at startup have over 500 PSI charge pressure after the machine heats up. It will shoot the error code low charge pressure and shut down if I stop working the machine and rev it all the way back up. It will go up to above 400 and run fine however, if I return it to idle it Drops to blow 200 and shut off
I got a good deal on the machine, knowing that I might have issues
Previous owner had pumps rebuilt, and drive motors replaced. I’m leaning towards pressure but wanna be sure since pulling the engines not going to be fun.

Check your hydraulic fluid for proper level, next, check belt tension for charge pump.

Verify pressure with an actual Guage, could be a sensor issue. Course that would be too easy.. . . Pull the charge relief valve (back center of pump) maybe just change it. I've seen some with a stack of shims where somebody was struggling with it.

Check case drain flows from both drive motors. I know they're new but. . .

might want to take a look at the fan(charge) filter and check for debris.
sounds like a bad charge pump to me

Well, was moving the machine out of the dirt piles to take it up to the shop. Everything quit moving no lift functions. Brakes would release underneath machine fluid pouring out of it bucket stuck on the dirt pile just got it backed up fluid out of the side of the pump.

Release fluid dripping underneath machine had to take the door off climb out the front so much for small repairs

Trying to figure out why this is changing what I type the brakes would not release