I have a Kohler Command Pro 15 (CV15T) on a 36" Scag. The crew says that it will simply stop running all of sudden(Spanish to English) and then they can't get it to start. Both times by the time they got it to my shop it started right up and I ran it for around 1 hours and back to them. The engine is 27 months old had rings and valve job and new carb put on a few months back. I sent them back out today and I have showed them how to disconnect the connector that takes all the switches and interlocks out of play so they can see if it will start. It ran all day today no problem. I guess this sounds like a coil problem especially since the fails happen after a few hours of operation and we are running 100F. Is the only way to tell if that coil is bad is to quickly drive to the failure and see if I got spark? It is going to be hard to see spark out in sun. What does a coil cost? Is there some kind of spark tester that really works--can be seen in daylight. Mine has to be in a dark garage to see the spark.