Hi guys. I've got two Duo-RX systems, and this seems to happen with both of them. I can take a clean Hucard, put it in the slot, pull it right back out, and it's still clean. But if I leave it in for a long time, and particularly if I play the system a lot, the Hucard's metal contacts will have some adhesive-looking goop on them when I pull the card out. I've noticed this most with my arcade cards, of which I also have two, and which I have left in the system for the longest times.
Where is this goop coming from? Is it some kind of adhesive leaking out of the card itself? I opened up one system and didn't notice anything that could be the source of such goop, although I didn't check as thoroughly as possible. The goop is thin and mostly transparent, and it rubs off very easily. After it appears on a Hucard, it's usually on the system's contacts as well, but that's also easily cleaned.
It hasn't really caused any problems so far, but I feel like this is something I should understand. Any ideas?