I started the first thread in countzero's list last week. As the thread ends, I pulled the 600 motherboard and shipped it to Amiga Center, France for repair along with my A4000 mboard which was losing sound and the par: port.
Good news is I'm told they sound repairable.
While looking around the web this afternoon I found A600 mother boards (refurb) at Amigakit.com. I just ordered a spare.
Bob