I think I have worked out which they are and have now run the unit with the minimum amount of cards as per the Tech note.

Still nothing on the digital output when calibrating.

As I don't have spare cards lying around I don't think I can go any further with this as I would need to swap out the cards one at a time to find the faulty one.

Lounge: DSP5200, 518
Snug: DSP33 x 5, C61R, HD621
Office: M33