First, you must locate your loom's serial number. To do this, follow these steps: 1. Face the back of the loom (side opposite the treadles). 2. Locate the lower back castle brace (lowest brace that runs parallel to the ground between the castle uprights). 3. On the right-hand side, look for a serial number imprinted on the top of this brace. For a time, the serial number nomenclature consisted of three things: model, last two digits of the year made, and the loom number. For example, A 76 123. This serial number would indicate the loom is the 123rd Model A made in 1976. If your serial number does not look like this, please call 603-827-3333 or email help@harrisville.com to have our loom specialist look it up for you.