You can try a local parts shop or search one of the many internet retail sites that may have one available for purchase.
I would first check on ebay.com Ebay pretty much has everything & anything :)
you could try online. or just order a new machine
Most Allen Bradley parts are of high quality and durable.
You can most likely purchase an auto parts dictionary at an auto parts store, such as Advance Auto Parts. Sometimes you can purchase them online from mass retailers such as Amazon.