Well, my receiver arrived Wednesday and I set it up in the Home Theater Thursday evening. Everything seems to be working fine. I was going to run Audyssey, but it sounds so good I'm going to wait.
I bought two external fans and placed them directly above the HDMI card. The unit sits in a rack whose back is in an 8x10 climate controlled storage room. There's a short shelf 4" above the unit, so the back half is open to the room.
I really hope this fix sticks. I'd like to get at least a couple of more years out of it. I may add external amps, but I've read that the chip on the HDMI board gets hot on its on.