Sonic Frontier Line 1 needs service

Recently, my Line one has developed a distorted sound in both channels.It sounds like it is struggling and volume level seems limited. I changed all of the tubes with fresh tested ones and the problem remains. Otherwise all functions are normal and all tubes light up. Any clues anyone. Secondly, I don't really want to send this back to Canada for repair. Can someone recommend a closer repair facility? I live in Miami, Florida. Thanks all
Try contacting Tom Tutay,at 850-244-3041. He does upgrades and repairs on all kinds of tube gear and he's in Florida. He's super reliable, in fact he's the East Coast repair center for Air Tight. Good luck!