I’ve rebuilt 717 and 787 pumps but this is my first time with an 851. The pump housing has 2 set screws in top and bottom of pump. I took the pump apart three times thinking I had crushed the thrust washer. It’s the set screws. If I tighten them down the impeller binds on the wear ring. Without them it spins like it should. Am I supposed to drill into the wear ring before installing the screws or is it fine to go without them?
