Thanks so much for that reference! I was beginning to think that I had some sort of Frankenstein sewing machine that someone cobbled together with spare parts. Not really, the belt holes all look factory-done. I just haven't been able to find any reference to that combination of capabilities online. The illustration you sent the link for is really encouraging. I had some trouble imagining reasonable circumstances where someone would want to shift from treadle use to hand crank, but your suggestion of "upgrading" sounds very plausible. I just wish I could find an official reference from Singer that they intentionally made components (the portable base with treadle belt holes, and a table/cabinet that would fit a portable base) to work together that way. Thanks again!