Leak between seal plate and tank body

I have a Sta-Rite Dura Glass pump with a new seal plate, seal plate o-ring also a new diffuser o-ring. The seal plate is pre-98 (with the cone) new p-100 shaft seal.  When assembled I have a leak between the faceplate and the tank body plate. No matter how much I tighten the locking ring, water is still coming from between the faceplate and tank body plate. I know it’s the right o-ring. I’ve had this apart 5 times! There are no cracks in either the faceplate or tank body. We’ve thrown a lot of money at this system and being seniors on a fixed income makes it impossible to have a new full pump assembly installed. I need a fix for this, please. Suggestions? Thanks.

We are sorry to hear that.  Be sure the o-ring has some lubricant on it and that it did not get pinched or fell out of its groove when it was reassembled.