looking for a Bias procedure for an ARC Ref110

Hi Audiogon Members
Happy Christmas to everybody
I friend of mine who has bought a Ref110 needs a Bias procedure for his amp as long as the User manuel didn't come with his purchase. Could you please let me know the meaning of the 2 trims which are present per channel. I don't know if each one takes care of the bias of a pair or if one is use for the bias of a quad and the other one for the imput and driver tubes setting
Many thanks in advance for your help
king Regards
Laurent