I've just signed up in the hope someone can help with my issue.
I must have bought a couple of dodgy SD cards once, since one of them started to break apart (inside my second SD slot).
Anyway, I noticed that the card would no longer push to eject. I had to manually grab it and pull it out. After disposing of this card, I could see small pieces of plastic inside the slot near the pins. I managed to get them out (I think, never did find the debris) with long tweezers. So now the push to eject works properly.
The new problem I'm now having, and to be honest it could have been happening for years but I've never run the camera with only one card before is this:
I remove the card from slot 2, and the slot doesn't recognize I've taken the card out, and keeps on throwing "card" "Err" messages if I try and take a picture without the card. Most of the time, I can put the card back in and it will carry on working. I can see that if I get 2 cards in again, it will become transparent, but I would really like to fix it.
I've updated to the latest firmware with no luck, and I cannot see anything in the slot that looks like it could be tricking the camera. Is there a sensor in there that I may have damaged and this is giving the false reading?
Update: I have been in contact with Nikon, who had me go through all the usual troubleshooting. Anyway, still not working. They have given me an indication of parts and labour for a new SD module, and that is approx GBP 160.00.
I'll have to have a think on that, especially since I have a workaround of sorts.
Update: Contacted Nikon, who wanted the best part of GBP200 to replace the card reader.
Sold it on eBay to a camera shop in the end. Just not economical to repair to be honest.