Another option might be Bill Baker at Response Audio in
Endicott NY. He has done nice work on upgrading/revising
Antique Sound Labs amps, and had his own line of Bella
Extreme amplifiers. Knows his way around an electronics
bench!
Oh, and I can vouch for Approved Audio Services in Bantam
CT. He did a great job of aligning and tweaking my Tandberg
3001A tuner, which is a beast to work on. Much cheaper than
some alternatives I explored, too.