[Damallooo]

Wow, that looks promising. I'm now fairly confident that it is the problem I've been having, because a) the interface has worked fine for almost two years now, without issues and b) I shook the interface like someone suggested in that thread, and I could hear something light moving around - quite possibly a wire. And since my warranty has expired and there are no authorised repair centres up to a few countries around here. So I'm going to go out on a limb and try this right now.

Thanks, Darryl. You're the man!