One of my 41's doesn't like modules in port 4

[damaltor]

Update: Though i was sure to have tested that before, i did now plug in a quad mem module into port 4. This produced the exact same results as with the card reader: The calculator made a faint noise, didnt turn on, and could only be reactivated by pulling out the batteries for >5 minutes. Removing and directly re-inserting them is not enough - it only brings garbage to the display.

The quad mem module works fine in all three other ports.

The contacts in port four look fine, and the calculator did not suffer from heavy battery leakage as far as i know. There was a rechargeable pack inside the calc when i bought it, and it had leaked a little, but not into the calculator - everything was still contained in the battery pack, and the battery contacts look like new.