Replaced voltage regulator,electronic PTO clutch assembly because the mower runs great until PTO was engaged,then it would kill engine instantly with or without driving it in any direction. After new parts were installed PTO will not engage at all but engine still starts,runs an drives great.everything seems to be all connected properly an no signs of corrosion at any electrical connectors anything like this happen before or is my sorry a$$ luck that ive installed a new defective part?