LHS Horn problem

[granthar]

I read through this post as my 78 horn doesn’t work. I disassembled it, everything like new inside. I reassembled without the chrome cover and adjusted the screw to set the points so they are opened during operation and a got a (rather weak) tone. As I refitted the chrome ring and tightened down the 6 screws the tone increased in pitch and completely stopped when fully tight. Pinching up the screws doesn’t allow enough movement vibration. Can this be adjusted with the large 21mm back screw or do I need a new thicker gasket? I confirmed the electrical circuit

[NobleHops]

Read Aris’ post that I linked earlier in the thread, that might set you right.