Tube amp blaring noise when i turn the stand by switch on!!!

[Spazzzz]

So just got a bugera bc30 and i turned it on for the first time and everything was perfectly fine it worked great. I turned it on for the second time and let it warm up (yes i let it warm up the first time too) but when i hit the stand by switch it starts blaring noise. I'm not talking about a hum or anything mild. I mean its super loud. I have no idea whats causing this. Please help. I have taken it apart and made sure the tubes looked good and all that. Made sure they were in place and everything. Once again please help.

 

[jeff5may]

Is it under warranty? If so, don't do too much to it or you could have problems getting service.

 

[Spazzzz]

No it isnt under warranty.

 

[JonSnell Electronic]

If EL84/6BQ5 output valves, probably the screen grids are arcing. Tap them gently if if does it with the master volume and effects volume turned down.

 

[Spazzzz]

OK. Will this potentially fix it or will it just show me I need a new tube and if it just shows me I need a new one what am I looking for to tell me it's a bad tube?