Repair for n Art Audio Jota in Los Angeles?

About a month ago, one of the two Mullard GZ37 rectifiers in my beloved Art Audio Jota started glowing bright red and emitting awful sounds. I shut the rig off and ordered a replacement tube. That worked fine — for about three weeks. Last night: same awful sonics and heat and bright red glow. I’m assuming that there is something other than the tube itself awry here.
Might anyone recommend a good, honest, well-organized repair shop in Los Angeles? Grateful for your wisdom and guidance.
With thanks,
Howard.