Re: Weird pickup thing. Is it normal?
It is normal,
If we think to same thingy, it is screw that can go in or out and its purpose is to even string to string output.
If one string is too loud or too quiet you can adjusted output with that screw. Some pickups have one or both coils with non adjusting thingies like your midle pickup.
Answer to other question is that pickup cable can sometimes pull pickup down or push up. So make shure that pickup cable is free to move with pickup by opening back cover.