There's a wiring diagram under the cover of the stoker timer that deals with what's in that box. The 77 otherwise is extremely simple. There's a line hot/neutral going to the fan control for the fan, there is a limit snap switch on the front of the unit under the covers that shuts down the stoker motor if it hits the high limit which is just a hot loop from the timer/relay output -> high limit snap switch -> stoker motor. Let me know what you need to know, there were some differences over the years in how they were wired.
I typically rip all that out and use a combination fan/limit control to control the fan and shut down the stoker under overfiring conditions. You can also add a low temp snap switch to shut the stoker down in the case of an outfire, but, with proper coal and making sure to leave a deep bed of loose ash (only pulling the clinker) outfires don't really happen.