Thank you very much for all the info and suggestions! Strangely, the Nav seems to have fixed itself yesterday while our exhaust guy was driving it down to his shop to make a small adjustment. The car left with 0 sats, I got it back with a full cluster and perfect accuracy and tracking. He didn't do anything, but I'm hoping it stays this way for a while!

I'll see what I can do about a software update as soon as I get back from MFest, couldn't hurt!