I have four different Erie clockface pumps, models 10, 603, 753LP and a 753. The later pump was purchased from you and brought to me, from the last Hersey show, by Chris. The first three pumps all use the reset knob pictured. I just went out in shop and tried to fit this knob to my 753as well as my 753LP and it fit perfectly. It has a reverse thread and screws on until it bottoms out on the stud. Your knob looks like someone may have tried to use a screw driver to get it off and may have only ended up tightening it. Try some penetrating fluid and heat and it should spin off in a clockwise direction. Hope this works for you.
Last edited by Hardy's Garage; Wed May 04 2022 01:56 PM.