HP-82104A Card Reader Repair Questions

[Papymouzot]

Easter update:

I opened the only card unit/motor I didn't open it before, just in case the pressure on the screws may change something. The card compartment looked clean, no residue from the gummy wheel. I cleaned the head with a cotton swab and isopropyl alcohol, put everything together and test again.... First tests, card err, but on the third attempt the card got read properly and it requested the second track.. it read the second track and the program was inside the 41. I tried writing the program to another card, did a "memory lost" and tried reading it again.... it worked. I hope this will last !!

I have now two readers working out of 4....

I was left with one giving "malfunction error" and one giving "card err".

I tried swapping the card/motor units and the error type is once again dependent on the card/motor unit and not the electronics. I really should have tried this swap game before... I only did it in between the two readers giving "card err" !

I opened the card/motor unit giving "card err" and cleaned it thoroughly although it was quite clean already. Put everything together, and I have something new.... depending of the position of the eccentric pin I get "no room" or "card err" but it can't be reproduced with precision for the same positions of the pin.

I have tried turning the pin a very little bit at a time, but I only get either no room, or card err... and yes, I checked the available program size... plenty of room available... and I have also tried with a working card reader, and the card /program was read without any problem...

I opened the card/motor unit which was giving "malfunction". and regardless what I try, I still get malfunction....

So definitely I made some progresses but I am still only 50% happy...