Try disconnecting the cable or linkage for the inching spool altogether & see if that makes a difference.

when you cleaned / changed the old screens what did they look like?
alot of debris in them?

All screens have been changed, shifting is the same as inching pedal-slow to engage. Figured out it's a pressure problem, only thing left is the pump.

when you changed the fluid (an assumption since you said you put in new fluid?) did you clean the sump screen at the base of the case? It is located behind a plate with 3 bolts holding it on. These are notorious for getting clogged up after a while if there has been a long interval between transmission services. Or was the filter screen you speak of the one located at the strainer/fitting located under the solenoid valve ?.


what pressures are you getting when you do pressure test?

there are 3 test ports on that xmission control valve for checking pressure for main pressure, clutch pressure, and torque converter inlet pressure.

The one on rear of valve nearest engine is torque converter
The one next to it near the center of the valve is main pressure
The one towards the front near the directional solenoid valve is clutch pressure

checking at idle:
main pressure: 134 - 169 psi
clutch pressure: 132 - 166 psi
torque converter: 14 - 72 psi

checking at 1600 rpm
main press: 145 - 188 psi
clutch press: 142 - 185 psi
torque conv: 14 - 72 psi

you will need to check these pressures to correctly diagnose the problem if it is pressure related.

How is it if you shift forward/reverse without touching the inching petal?