im having trouble wth a 25hp kohler command engine. one of the cylinders doesnt fire. i checked spark its perfect. not sure about the gas but on the plug it seems to have enough. i did not compression check it yet but could it be the valve lashing not letting the exhaust out enough because it will fire after every 6 or 7 revolutions of the other cylinder?model # CH15S SPEC # 68503 Family # SKH725U1G2RA any suggestion welcome!