Hey guys! So I'm reaching out to y'all as a last step in a nightmarish guitar problem I've had for months. I am not new to repairing my own simple guitar glitches, but I cannot find this problem. It began with a simple switch breaking on my Mexican Tele. It stopped working, and I decided to replace it. So, I went to my local guitar shop and decided to try a 4-way switch for fun. I took it home and installed it with the diagram below. I noticed a grounding issue (constant buzzing unless touching anything metal) in the 1 (bridge position) and the 4 (bridge/neck in series) position after I plugged it back in. So I took it apart and started checking and rewiring everything I could think of, checking it as I go. I found some small things that I forgot to do the first time, like grounding the neck pickup cover. Then in all my re-soldering, I realized that I over soldered a pot and made it ineffective. So, I replaced the pot. Then I continued to try checking things with a multimeter and alligator clips before finally giving up and taking it to my local shop for repair. After he looked at it for a couple days and charging me $150, he couldn't find the problem either. So Im stuck with a couple options: I could try buying a regular 3-way switch just in attempt to make the buzz stop, or maybe replacing the bridge pickup to see if thats the problem. Again, I have tried grounding everything possible and have tried some ridiculous things to make it stop. Needless to say I am beyond annoyed and perplexed with this problem. Let me know if you can think of anything else I could try to fix this.