Once the bypass valve is removed, a small putty knife or a gasket scraper removes the O ring easily. That's how I was taught to do it when I got my first job outside the family shop in 1962, pumping gas and doing oil changes and tire repairs at a Shell service station. I worked after school 5 days a week, and had alternate Saturdays or Sundays off on the weekends. Kinda rough on the social life, but I had a 47 Ford business coupe to feed and insure! It wasn't uncommon to find two gaskets in there!
Jerry
