hey guys i just had a new shortblock installed in my 2005 800 summit. i have rode the sled 170 miles since the install and the pto side stuck. i let it cooldown and worked the clutch back and forth and it came loose. the plug has all kinds of little alluminum spec on it. the motor is completely stock other that a spi pipe. i was running stock jetting and the plugs were real dark brown prior to the happening. what could have caused this?