I have a Scag walk behind mower that has a 20hp Kohler and electric start with the hydro pumps. The problem is that alot of the electrical system does not work properly. Sometimes they do but others they don't. The battery does not always charge. The clutch will not engage. The OPS will not kill the engine with or without blades on. The engine will run on for about 15 or 20 seconds after I shut the key off. I have switched the battery, voltage regulator, starter switch, installed a new clutch, and replaced the starter solenoid. All to no avail any help out there?