On Sonic Frontiers many would recommend sending it all the way to Canada to Chris(partsconnexion) as he was the owner of Sonic Frontiers. The shipping itself of 2 units to begin with. The total repair-shipping toll may run upto $1500
1. Check if your tubes are still good
2. Check bias voltage
3. Research if you can find local tech to restore your amp. It's not complicated and if you spot someone on Craigslist selling restored vintage tube amps, one might be able to try to fix it.
4. I repair vintage solid state and tube amps, turntables, RR and tape decks in Raleigh NC.
You should try at least for the time being using solid state to drive Avalons having following facts:
1. you've got tube sources and preamp
2. Avalons benefit more from solid states than tube amps.
Other than that I believe AudioResearch models may be a better match vs. SF power3.