You have a lovely collection of machines. I think you are up to looking at the 319. It takes a bit longer to sort out cleaning and oiling, but within what you would expect. I know some have had issues with timing on these and damaged bobbin case, but once sorted out they have stitched reliably. There's the issue with needle type, if 15x1 is used it will damage the bobbin case unless it's adjusted for it (how do you check for that?). Originally they all took 206x13.