What concerns me is that some of you are telling this person to bias to a certain level on his amp. It should be noted that bias levels are not universal from amp to amp. No Hickok ever made will properly test most power tubes which would include 6BQ5s. Now this doesnt mean that a tube wont continue to be linear as the plate voltage is increased from tester to tester, but most suitcase testers will not give you an accurate reading because they dont test at real world operating levels.
For the record I do not like amplifiers that can accommodate a wide range of power tubes. Some have pointed to the possible problems and shortcomings of such designs. However, when in doubt it is a good idea to listen to what Ralph at Atma-sphere has to say on the subject.