Amp/Preamp Asylum: Missing Bias and hum adjustment on AQ1008 845DT by Grummer

Hello,
there happen to be a AQ1006/845 monoblock which i sold last month, little did i know that the hum adjustor and bias adjustor were removed!, (no wonder what those 3 holes on the side were for) i feel pretty stupid about it. the guy how bought the amps is mostly happy and will get it adjusted, he's not returning it so thats good and so I decided to help abit but making enquiry here hoping someone who might be able to guide whats involved.
Does anyone have had experience with these amps (I am aware Jack G did, not sure if you still got yours), also I am aware that Joesph Lau worked at ASL, designed these amps circuits (am i right?)

Really please, give advice, so I could pass it on (copy/paste and email the guy who is going to have it replaced with new adjustors and so he could take the infomation to the expert repairer (hard to find the in NZ!, lucky for him to know where to go - i didnt have a chance) I hope its not a big modification because it would be a drag down. It is the last thing i want is an unhappy buyer as i have now gone deaf, i cant hear anymore and wish someone enjoy these great units.

So please help.
Many thanks,
Craig