Thanks, Miriam. I will have to keep a lookout for those big zipper feet for those machines. I'm thinking that may have been the reason that I kept finding machines and/or attachments for a while that had three zipper feet in them. Probably they kept getting the narrow ones, and didn't bother to look for the ones that actually worked for their machine. I think some of the Kenmores, too, came with wide zipper foot and yes, there is definitely more metal behind those to be able to feed.
Janey - Neat people never make the exciting discoveries I do.