Tomas Tomosoy had a series of them. They're published by Amherst media.
Camera maintenance & Repair vol l &ll
Restoring Classic & collectible Cameras
" the Great Collectible Cameras
Leica Repair Handbook.
None are especially technical but introduction type guides.
National Camera Repair School also had a series. If you go that route the one on leaf shutters may be the best OR overkill. It'll have a lot you won't need.
If you want to try quick & dirty, remove the front group and flush clean it.. Some folks feel it's heresy though.
Doing the Q&D you're putting a drop of lighter fluid onto the shutter blades and cycling the shutter. Ya gotta do this until all the fluid has evaporated
or the blades will stick together. Don't go nuts with the fluid, small drops and you may have to repeat a couple of times.