Ditto. It is usually something simple. We had one sled where the connector on the back of the key switch kept sliding off. It looked like it was on, but it had slid forward far enough so that it wasn't making contact. On another sled, the wires in the socket on the engine were not locked in. So, when we tried to plug in the connector from the wiring harness it would push one or two of the spades out the other side of the engine connector. That one took a while to figure out.