Case 621C instrument cluster problem

Hi Guys, My 621c instrument cluster (part no.278823A4) has gone blank also disabling trans and bucket controls. Engine starts and runs. Instrument cluster will light all readouts and warning lights when program switch is pushed, will also show correct readouts of oil press, temp, trans selection etc when program switch is held down but won't allow trans or bucket movement. Once program switch is released, screen goes blank. Buzzer sounds continious. Fuses, relays, earths all checked, cleaned and good. Power and earths to IC are good. Case tech manual resolution if power to pin 1 and 2 on IC is good (which it is) with blank screen and no trans/hyd controls is to replace IC which costs $5000. I have to order this from USA at my risk, if it doesnt fix it, tough luck. Has anyone seen this and does it sound right? Instrument cluster does contain computer that controls/overrides trans/hydraulics. Machine is very tidy and in excellent order with 5700 hours. Before this everything worked perfect.
If anyone can confirm this would be much appreciated

Case 621C instrument cluster problem