Excellent guide, thanks much Vid!
I realized quite a few people have also problems with the switch arm functioning, near the bracket. It can happen that the bracket slightly pushes the switch arm just enough to activate it, creating all sort of logic problems during gameplay. Therefore be careful using the correct switch arm and adjust it properly.
Here pictures on how it is supposed to work:
https://pinside.com/pinball/forum/topic/the-shadow-club/page/69#post-3538379