Andrew, I bought an A1 with the same problem - no cover. Call some of the used camera dealers on Ebay. A goodone I use is Woodmerecamera.com. He does repairs (light) so he can sell them so he might have some parts.
I bought my AE1 from him and it works great. I bought an A1 at a consignment store and it does not focus right. Every picture is blurry? It's not me because I took same picture with AE1 and no probs. Any ideas why? Prism problems? Cost to fix?