03-23-09: JwmJwm is probably right. I had the same problem with one of my ASL amps. VB1 wouldn't move beyond .002v after swapping in a known good tube. After removing the bottom cover and looking at the circuit, we could clearly see a burned out resistor next to VB1. We took voltage readings around the resistor and they were way off compared to the same points near VB2, VB3, etc. If you have a multimeter, and you're comfortable poking around high voltages that can kill you, you can fix this yourself by finding the resistor and replacing it. If you haven't done this kind of work before, take it to someone who has. You can probably find someone local, but if not, here are some suggestions:
the tube probably took out a resistor near that tube that blew.
http://forum.audiogon.com/cgi-bin/fr.pl?htech&1168541051