I had a faulty IR receiver on my MK2. It worked perfectly for a couple months, then died one day. I sent it to empeg in Cambridge and it worked for them (of course). They replaced the IR receiver anyway, and it's been good ever since.

I'm not suggesting your IR receiver is busted. I'm just letting you know what happened to me. I think the thread I started on the subject was called "Remote Control Oddities."

EDIT: Here's that thread.