danny
port1 140>170 psi (pump pressure. next to dipstick
port 2 105>125 psi (forwrd clutch. front of control valve next to dump spool)
port 3 105>125 psi ( rev clutch. down below throttle pedal off the control valve.rear of two ports.
port 4 105>125 psi (torque conv pressure. just across from port 1. behind filter
port 5 15>25 psi ( lube pressure. next to port 3 under throttle pedal
port 6 variable ( modulater pressure. below rear solenoid. varys on position of dump/inching spool

hope this helps mate but still reckon that circlip has come out. quite common problem. mast off job. easiest way is to drag transmission out the front leaving engine sitting. with practice you can have transmission on the floor in 2 hours. no need to strip brake hubs off or pull half shafts.if you get stuck just shou back