Hello R.,
Welcome to the forum.
If I am not mistaken, this is a low output stator on a Briggs and Stratton that does not have a separate voltage regulator. It has an inline diode on the red wire hiding under the shrink tape (near the white connector). That diode is bad and allowing power to flow back to the stator when it should not.
It would help greatly to provide us with both the product identification label information (usually under the seat) and the engine model and type information that is stamped into the valve cover.
MTD made 100's of different model mowers, and it is a guess which one you have.