My M&S 100 has those markers. It’s a pretty rare pump but Jack Sim says it was probably a Doty pump design because they were bought out by M&S in St. Louis back in the day. So maybe some Doty pumps used them too. Doty’s are pretty scarce too. My pump has an etched cylinder also so it only had two marker sticks opposite the etched markings. Don’t know if that’s normal or not....GB