Pfaff 1222 or general light switch replacement collar - READ

thingiverse

I would NOT recommend taking this switch apart to repair, but they seem to be harder to find. So you'll need all the parts if the top broke off like in the picture. There should be a spring, and a very small metal plate (~4mm) with catches on the top of it. This switch has 4 springs, and I think near 30 parts. Classic German overengineering! This is actually a rotary switch, so you could just simply print a knob that slips on the twisted metal piece and live with that. Once you remove the spring clips on the sides be ready for the other springs to send small parts flying. I'd recommend clamping the ends beforehand. let me know if it saves a vintage machine ;)