HP 41 Card reader problem

[damaltor]

I had a similar problem. When i inserted the card reader, my calculator wont turn on. It is a 41 which is in very niche shape and works nicely.

In the end, the problem was not in the card reader but in the calculator: The calculator simply will not work when anything is plugged into slot 4. The device is in perfect shape and there is nothing to be seen inside slot 4, but still it wouldnot work. The card reader works nicely with a different 41.