I own 2800 watt brushless Yamaha generator. Its about 12 years old. The engine runs fine but the generator will only output at very high rpm's. This happened overnight for no apparent reason. I have a repair manaul and I've checked the stator, rotor, capacitor, rectifier for the 12 volt dc battery charging, wire harness, breaker and receptacles and all check ok according to the manual. The only thing I did not check are the diodes and capacitor on the rotor because they are solderd in place and the only way to check them is to unsolder. I have also flashed the field according to the manual. When I apply 12 volts to the capacitor the voltmeter on the generator registers about 30 volts but drops to 0 when I removed the 12 volts. Please help me figure this one out.