Thanks to Z, I have the ART-13 (actually an ATC) up and running. Found out today that is works in the dynamic mic mode but carbon side is dead. Bias is there but no audio. I understand that the unit was probably modified to "improve audio quality" at some point. Hence the request for a replacement module. If no tubes, that's fine. I can purchase or trade. I have knobs, meters, mod xformer, autotune motors, and a few other items. Any port in the storm. TNX