Question about a Dynaco Stereo 120a

Anyone know what the four green wheels(dials) inside the amp are, and how to set them?

As far as I know, there are no user-adjustable parts inside that amp. The "Green Wheels" may be the filter capacitors and you don't adjust those. If the amp sounds okay, it may be best to leave it alone -- if not, find a schematic and take it to a qualified technician. :)
I have a friend who I sold my 120 amp to and it had the schematic. If you need it, let me know and I will see if he can send you a copy.