I have that thing etched into my memory to the point that I probably could still fix a beeb without resorting to looking at the schematic.

Indeed they seem to be:

https://chrisacorns.computinghistory.org.uk/docs/Acorn/Manua... ("BBC Microcomputer Model B +")

There is a circuit block diagram, a PCB layout diagram with all the components' part numbers that I guess you can replace broken ones (?), and circuit diagrams for the power supply and for the keyboard circuit. (starts on page 97) Skimming the text, the manual seems to assume an owner has access to a multimeter, an oscilloscope, and a soldering iron.