When rewiring a machine with or without a schematic I carefully disassemble what I need to disassemble to get to the wires. Then I study the old wiring and make my replacement wiring match. I route it the same, make it the same length and try to use the same type of connectors if possible.
It's not that hard.
To avoid confusion sometimes I'll use a silver Sharpie and mark each wire so I know where it goes to.
Or a digital photo of the original mess to use as guide. Lots of easy ways to do it.
As for wiring diagrams I have quite a few. But they are stored on my computer as pictures. Some years ago I lost all the URLs so I don't know where I got most of them.
Joe