Seeing as this is your first post, I'll tell you this so you don't think you are being ignored.
No one wants to look at schematics for those types of marshall circuits because of the way the connectors are drawn. It's very hard to follow the signal unless you have a lot of time to spare. If you get lucky, you might find someone who is very familiar with this model that could help you.
Meanwhile, here is what someone said about which part of which tubes do what: