One of the main points of the engine flush was a stuck relief valve causing zero pressure, FWIW...a good friend use to use Jasper engines but overall had a 30% failure rate of those he installed. He now uses a company called East Coast Engine in philly. Years ago when I worked for Mazda we had a big problem with filters made in Israel. The check valves would loosen causing major fluctuation in oil pressure. I looked at my Ex and it appears the pump could be removed by removing the front cover and removing the pan bolts and just jacking the motor allowing access to the front pump bolts without removing the motor. Worth a try if needed