There isn't a public schematic for this unit. Klark Teknik has it on lock down. You can refer to the original LA2A schematic on some of the circuit, but the labels of the semiconductors wont correspond with the Klark Teknik circuit, so you kind of have to follow the circuit to see what is what. If I were you, I'd worry more about the opto and the big cheap yellow output cap off the output transformer. I noticed some improvement in the low end from changing out the electrolyrics for high quality nichicon ones, but as mentioned by KingKorg, it may have been that one of my components was slacking, and may not have been necessary for all the caps.
You'll have to recalibrate your unit after installing the new opto and you won't be able to get the GR meter to match perfectly without changing out a resistor. I'm just living with it and keeping aware that I'm getting about 1db less GR than it says.