Hmm, sounds like it could be more serious than that, but you really never know, and upgrading FW would be my first advice as well. I just gave my BD30 to a friend as a gift very recently, and I updated the FW for her convenience, but I am afraid I already threw away the disc. I would've sent it to you, if you desired.
I think it will most likely be an absolute waste of time, yeah nm, I was going to mention trying different ports, but that seems dumb to me, ok nm.
I thought I was bad about updating FW, but you're making me feel better about it now.
I do think 1.6 was the bare minimum, IIRC, as it might be the update that fixed the -5 db LFE cut.
Sorry man! I hope FW might be a miracle cure . . .