That is one of the most useful and entertaining books ever written. My VW once ( well, often) exhibited bizarre behavior. It started right up but stalled as soon as I gave it any gas. Puzzled I opened up that book without much hope. Under a heading of “starts, won’t run” I was instructed to put the end of a screwdriver against the carburetor bowl and whack it moderately with a hammer. That fixed a stuck carburetor float and I was on my way.
I used that book and the JC Whitney catalogue to rebuild several VW engines.
A ball point pen stuck into the butterfly valve worked well too.