[BC] Te st your wits on this

[Milton Holladay]

Two possibilities come to mind:
!]  the drive circuit was damaged incidentally when the filament contact burned up and is causing some sort of spurious emission
2]  there was something simple yet subtle done wrong in the assembly of the filament contact which causes something spurious.
Is there any outside possibility that the burned contact was a result rather than a cause ?  (trying to think outside of the box, here...........)
M