I saw on other videos where the core plug was remove to use a socket on the impeller shaft to install the pump into the pulley on a press. Innovators directions online said to just shore up the core plug to keep it from being pressed out when the pulley was pressed on. I called their tech support and they confirmed. Maybe overkill but this is what I did to shore mine up. I used a washer and sheetmetal until I got my straigt edge to touch across the back of the pump.