trying to fix NZP55 card problem

I have a problem, with my Deckel FP4NC (DIALOG2) serial-number10168 year1984.

The Z-axis don't appear anymore on the display.

There seems to be a problem in the Z-axis NZP55 card. (zahler-karte/counter-card)
I already switched it with the Y-axis card, the failure moved to the the Y-axis and the Z was okay, so I have to look further at the NZP55 card.
Does anyone have a scheme, for the NZP55 card? (or the later used NZP58 card)
Any (tips) repair info, would be very appreciated.

thanks Ysbrand.