another be100 footswitch question

[fusoid]

Hi Guys,

When i hit the footswitch to boost on my be100, it squeals until i turn the gain down to less than 5...any help would be appreciated...

 

[Adambomb]

The footswitch is just a passive switcher, can't imagine it's that. Must be a microphonic tube in V1 through V3. Get a good 12ax7 and swap until no squealing.

 

[fusedbrain]

Hitting the footswich for the HBE channel brings in V1.
Probably gone microphonic.
Swap out v1 with a known good tube and see what happens.