[Amps] setting bias in Alpha 91b

[Fortra]

Hi Guys,

well, all good things have some terminal failure, thus my Alpha 91b.

Made in 1995, with original GU74B's  which went south recently.

After quite some googling and seraching in amps. archive, i could not find 
procedure to set up bias per tube in NOS GU74B!

I faintly remember seeing that somewhere, but could not find it again, and as
the collective memory is better googled i am asking you for a procedure!

Yes, mail went to Alpha as well, but let us say i am bit impatient for results and instructions!

Thanks,

Nermin S58DX