Roadster - Strange Noise when engaging on/off effects loop .

I'm getting a soft "frying egg" sound whenever I engage the loop system. I'm suspecting the V5 (loop driver) maybe worn out. I'm planning on removing the chassis (which is a pain, since it is a 1x12 combo) and do a tube swap to see which one gets rid of the issue. I have to replace the reverb tank while I'm at it so it is a good time for doing both tasks.

Do anyone else has found this issue on their Roadster? BTW Should I look elsewhere? Thanks!

Had your same issue here.
Solved by a professional tech who replaced a resistor in the fx loop circuitry.