They do break up easily, but it is still capable of clean. Hopefully it's something as simple as new power tubes and bias, or maybe some preamp tube rolling. The tone controls are passsive-cut only, so they take some tweaking. I usually dime the bass control and play with the mid and high. Traynor doesn't publish the frequencies, but the mid freq seems pretty high, so adjusting it can tame some of the inherent brightness in addition to the treble control. Hope he gets you sorted quickly.
Mid @ max is theoretically 'flat'. I leave the Range at minimum and crank the bass as well. That should approximate a flat line with an upwards low-mid slope. I did punch the numbers into the tone calculator a while ago and it seemed to back up my impression.