Volume and gain drop in Road King

[MesaMonster]

I was practicing for a gig this weekend when my RK suddenly lost volume and gain. It had been working fine for about 30 minutes then started dropping out. any idea what that could be. Am I losing a pre-amp or power amp tube. I am using channel 3. Thanks for the help.

 

[easchow]

Loss in signal in one or more modes of the amp usually points to a preamp tube failure. You can use the tube chart in your manual to see which tube needs to be replaced.