I have a 582 in my Kitfox with a Westach Quad gauge. The last 2 flights are showing an RPM drop of 1000 on one mag but only about 100 on the other mag, yet I can tell by the sound the drop is about the same. There is only one tach lead from the engine so I don't know how it could be the tach. I am wondering if there is a flaw in the ignition/electrical system that would cause this. Any help would be appreciated.