Mark - That ground/earth wire should be FIRMLY attached to the bridge, and to the ground/earth point in the guitar's electronics cavity. Switch clicks usually come from some bit of ghost voltage that discharges into the signal. A poor or weak ground/earth wire could certainly cause such a problem. Mucrophonics would probably be a different problem. Sounds like you could use a checkup with a good electronics-savvy repair person. Good luck!
"Without music to decorate it, time is just a bunch of boring production deadlines or dates by which bills must be paid.
-- Frank Zappa