Service manuals with test signal values - Marshal 6100

[mv4wd]

Hi everybody, I've fixed a few years ago a Marshall 6101 EL - 34 combo amp. It's an early revision with a dedicated screen grid power supply. I'm using the amp every week for reharsal, and even if it sounds good, I really don't feel like its output is al loud as a 100watter. I have a 50 W Jcm 800 combo which sounds way louder and more 'open'. I admit the master volume taper and the speaker are different and more efficient (RedBack vs Eminence Swamp Thang). Still I might have some hidden problem. Tubes should be good (last time I checked they all measured the same idle current). My question: is there any specific or generic service manual/schematic that shows test signals values? For example, apply 100mVpp to input, all controls to max, that's what should measure at V3 or PI. Next week I'm testing the amp with a proper power load just to check that I can reach about 100W output @1Khz entering the return of the preamp. I remember something similar in the book of Marshall but was for early models.