I picked up a huge, huge archive of Leica paperwork / ephemera a while back. I don't have time to scan it as I'm busy with my own photography. But I got a couple of service manuals scanned.
Here is the M3 Manual
https://photographysgoldenageii.wordpress.com/2019/02/08/leica-m3-service-manual/
Here is the M3 Manual
https://photographysgoldenageii.wordpress.com/2019/02/08/leica-m3-service-manual/