2096 Case tractor with 'Powershift" problems?

Have a 2096 Case tractor, 850 hrs excellent shape. IT "jumps" when you powershift up from 1'st to 2'nd. Not a smooth shift. Coming down 3-2 is more of a jerk.
Have ;
~ Checked both the 1 and 25 amp fuses
~ Checked pressue in P1-2-3- and 4 pressure ports, used 4 gauges, all psi on gauges was between 200-210.
~ Replaced relay board. Found bad relay wire T20 to # 1 onboard.
~ Tried a different selector switch-no change.
~ Checked inching pedaladj. and inching pedal switch adj.
~ Replaced pressure switch.
~ Did power clutch leakage tests - OK
Any suggestiong would be "greatly appreciated "we cannot track down a diag. module tester because of the tractors age .
Running out of hair !!!!