Help with Dolby schematic

Another chapter in my efforts to get tapes encoded with Dolby B noise reduction to sound as good as they can has led me to buy a Dolby 422 which replaced the 330 in Dolby's line up. Here is an internal photo, certainly looks like downtown Chip City:



The parts level seem very good, lots of Dale metal film resistors and WIMA film capacitors, I checked the power supply (this unit came with an excellent owners manual) and all seemed right on the money. I had the top cover powder coated and spruced up the front plate and it sounds really, really good.