How do I find a part to an old Eureka vacuum model?

I have an ancient (older than 20 years old) Eureka vacuum cleaner (canister style, model #1770). The plastic latch on the back broke 2 years ago. Since then, it has been held together with duct tape. Does anyone know how to find a discontinued part? Is there a warehouse or vacshop somewhere that might collect and hold such things? I live in a small town out west and the vac shops here do not have any parts for this machine. If someone out there has a broken down Eureka canister and would be willing to donate the latch, I would be so thankful! I would certainly pay for shipping.