JLG 45HA Hydraulic Issue

I have a JGL 45HA. I capped the ports on the drive valve, and when operated one way, I can get it to the 3000 psi it should be. When I go the other way, it only gets to about 2400 psi. I swapped a valve cap end with a different function, and added shims to the spring, but no change.

The odd thing, is when I function another function, it will jump up to the 3000 psi, but not the drive function by itself.

I was curious if the dump valve could be causing this, but it seems like it is...

JLG 45HA Hydraulic Issue

JLG 45HA Hydraulic Issue