There's an outfit called T.S. Computers in Burbank Ca. I used to work for them, we had a place to send broken Amiga motherboards of all flavors, and they always fixed 'em right the first time, every time. They weren't the 'cheap' place, but they were the 'good' place :-) They'd put sockets in for all the AGA chips, Buster, etc. if the mobo didn't have them (as most 4000s don't) and were just generally champs to work with.
http://www.vgn.comis the URL, click on the TS Computers option and go from there. You might have to call them, but they've got a guy who is Amiga savvy and can probably help you, or at least tell you who can. That's who I would try.
