Where can you find parts for a Marathon Products Inc kit 22 LR Rifle?

In 2001, General Dynamics bought Santa Barbara Armaments from the Spanish government. Santa Barbara was the actual manufacturer of the guns sold through Marathon Products (until Marathon went under in 1987). If you can't find parts through Numrich, at http://www.gunpartscorp.com/ you're probably stuck. In perfect condition, these kit guns are only valued at $55, according to the Blue Book.