Just got my 45 from Ceriatone and seem to have a weird issue with the master volume mod they installed. With the bright and normal volumes on zero and the PPIMV on zero I get a loud hum. With the PPIMV ON 10 the hum goes away. Gradually as the volumes goes up to 10 where it goes away completely.
See video for example.
https://youtu.be/yNH8P3QrsW0