You might have damaged the tube. Try changing the tube.
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You've damaged 1k resistor that you actually read the bias voltage from and tube as well.
You can order this or a few resistors from OM.
Check if there's no visual damage (leaks, blown like baloon) to electrolytics for offset supply of that tube.
Bias circuit in VTLs is one of the most amature and unreliable. Sending for the service to VTL will cost you half of your amp's cost minimum. Would not recommend VTL if there's no DIY electronic skills.