I thought you said the sound was coming from the head, The best way to tell exactly is to hold a wooden or steel rod to the point and hold it to your ear. the same way a mech finds bad lifters in a auto engine.
theres good builders and bad not going to slam anybody, dealt with all who have built these and had no problems with any of them. I mean trading and selling and buying with them!!
its a secret for me to know and the info will cost you! The builder that was is no longer, the new guy is?? His name starts with a G and he is part of this site.already 15 week wait for a full set new.
You would have to buy a whole system with the switch or retro fit a switch to your brake system at the foot pedal somehow and wire it in don't forget to get a new voltage reg with the extra wire.