A book was published during the war with a view to keeping sets working even if only on the local station.
Valve Replacement Manual For Radio Service Engineers Hardcover – 1 Jan. 1941
by A.C. And Arthur Woffenden Farnell (Author)
Doesn't seem available in the UK at the moment but worth looking out for.
https://www.amazon.co.uk/Valve-Repla.../dp/B001OZRSQY