There are several reasons we ask for the serial number. First, it allows us to find the original shop order from when the product was built. This shop order tells us the exact assemblies used to build the product. Also, we track the history of the product with the serial number. A log is kept of all parts sold for that particular serial number, allowing us to track if some part of the product has changed in its lifetime. The serial number allows us to determine if your product is under warranty as well as what repair parts to send.