I have a JD model LA140 riding mower, i bought it to fix a couple things and resell....well there is a problem i cannot figure out. This machine has a 23 HP briggs engine on it, the first time you go to start it up she fires up good and runs perfect, whether you run it 5 minutes or 5 hours when you cut the engine off it will not start back, just grinds and grinds. I removed the carb solenoid, cleaned and lubricated it but that did not help, so yesterday i put a new carburetor on it, thought that would be a sure fix......wrong, it still does the same thing!! What could it be? Its probably something simple but i have no clue what to do to it now!