After many days of fiddle-faddling and playing 123 Spider, I spent five minutes wrestling the ends of the tubing together and got my treadle machine going again!
Lowery's Sewing Center didn't have leather belts in stock because the Amish prefer stretchy tubing. He offered to special-order a drive belt for me, but I bought stretchy tubing -- for just short of twice what I paid for the machine in the mid-sixties.
I put the broken belt away for emergencies -- it could be lengthened by sewing the ends together with stout thread. I wonder whether there is some sort of belt dressing that would keep it from going brittle?
Joy Beeson