For what it's worth, I have a 45k-67 with a jump foot, and the removable rectangular base that converts it from a cylinder arm, to a flat base. Also have a 45k-72 in which the presser foot bar jumps up in each cycle, as if it's meant to have the jump foot, but it came with just a roller foot a bit under 1/8" wide, though I've been able to get a spoon foot, and a wider roller foot for it. The feed dogs on one of them had been worn to smithereens, and the plate had been broken where misaligned needles or leather over the years has walloped the hole. (I'm gguessing someone had tried sewing horse rugs, and the misalignment comes when climbing up a thick double seam) The plate and needle hole had been brazed back on a few times. I was lucky to pick up another plate and a few bobbins from an old Singer service shop, before it shut down 10 years ago. The fellow there kindly photocopied the parts book for that series (45k 67 to 45k 72) for me, though he charged me an arm and a leg for it too! I don't have much in the way of spares that are spare though. We have clydesdale horses, and I've made our own harness over the years - using these and also hand sewing, plus using a big old unbranded Adler/Wertheim with a sideways moving shuttle. I use a chopped down Pearson needle for that. (Also have a 29k13 that gets a fair bit of use, a Pederson sole stitcher, and a few other mostly dead middle-sized Singers.) Thanks for the thread. I had three days of 'fun' (sarcasm) 28 years ago when I bought the 45k 72, as I knew nothing about them, and the timing was out - it would not sew anything, though I was promised it worked. I just about tore my hair out trynig to figure the problem-eventually I found a loose grub screw underneath that prevented the shuttle from rotating far enough round at the right time to grab the loop of thread. Once I seated that, it's been fine!