HP-67 - 1909S02534 - Card reader advice requested

[albertofenini]

Hello Everyone,
after a bad moment in our lives with the loss of my father,
we re-opened our lab and started to work again on our toys.
Yesterday we restored an HP-67 that was in working condition but showing some wear,
you can see some pictures here :
HP-67 1909S02534 - Full restoration
However, the card reader, although rebuilt, it keeps giving an error message.
This is what RA and RB looks like :
   
   
What would you suggest to do ?
Thanks for helping us out !!!