One thing I know from trial and error ,Is that I can work any false signal and make it come through clean ,and sounding like a coin. ..I'm not a know it all but if I could pass on one piece of info,,if the hit isn't solid and good sounding from the first pass just keep moving. You can set there and isolate a false signal into sounding so good you'll end up digging some junk or chasing a ghost signal .. A good coin hit or nickel hit ,or ring for that matter will be consistent sounding from the door, no need to work it with multiple passes or the god awful wiggle, that'll get you every time