Gas valve parts can generally be found at any hardware store, such as Lowe's or Home Depot. However, if the part is slightly obscure and cannot be found, an online retailer such as Amazon or eBay may carry the part. If that fails, try ordering directly from the manufacturer.
Proper maintenance of one's furnace or oven is important for ensuring both functionality and safety. A faulty furnace can be a fire hazard, as well as being energy inefficient. Carbon monoxide poisoning is also a common risk for even the cleanest gas burning systems. To save money and to keep peace of mind, maintain or clean your furnace or oven three to four times annually.