case 1845c low charge pressure to left front circuit only

the case im currently working on has correct charge pressure to 3 of the 4 travel circuits only...right f&r are 340 psi and left rev is 340psi.....the left forward is cutting out to 160psi when lever is pushed forward...i disassembled the tandem pumps, gave thorough inspection and replaced all seals...after assembling and installing the pumps the same problem still exists, low charge pressure to left front forward only...i tried swapping circuit reliefs around and still same problem....any help would be appreciated....thanks

case 1845c low charge pressure to left front circuit only