About 1.6 hours into a flight, I will have the alternator go off line and watch my volts drop. I recycle the alt. (master switch) and leave alt. off for about two minutes, then cycle back on and I get the alternator back on line. I have had the voltage regulator and alternator and belt tightness checked. No problems. Mechanic thinks it is an old master switch and developing too much resistance. Any thoughts? Any similar problems out there? Its an 1981 Archer II. Brad.