I'll respond, even though a zig zag stitch is about as decorative as I get. I am not familiar with the 9124, but to me a vintage machine with patterns would be a Singer 401 or 500. I think generally the parts that might need replacing on these are still readily available, and the 500 at least, in addition to the built in patterns, accepts cams for additional patterns. I have one of these which I just cleaned up and it sews strong and fast.
I have a Singer 328 that uses cams for patterns, including zig zag, it is a machine I would consider. I have a Stylist 534 that I use (even though it has plastic/rubber gears) and it has a few built in patterns, but does not take cams. It is the only free arm machine I have which comes in handy, as when I fixed a couple of rips in some shorts (using the ZZ stitch); it is a very strong sewer.