If you have a pot that adjusts a grid negative voltage, you should make it less- negative and than you'll be able to get larger bias voltage(current).
If you don't have it displayed than you should probably open the pannel or let tech do the work for you to adjust grid voltage.
VTL do not require matched tubes since bias is done individually for each tube(you might probably only need matched pairs for different channels)
As to input tubz, I wouldn't suggest using the bad ones since they can do a further damage to the rest of electronics.
I used a couple NOS ones but figured that stock JAN-Phillips used by VTL never goes bad and stays almost forever.
If you don't have it displayed than you should probably open the pannel or let tech do the work for you to adjust grid voltage.
VTL do not require matched tubes since bias is done individually for each tube(you might probably only need matched pairs for different channels)
As to input tubz, I wouldn't suggest using the bad ones since they can do a further damage to the rest of electronics.
I used a couple NOS ones but figured that stock JAN-Phillips used by VTL never goes bad and stays almost forever.