since i suspect someone else might have run into this problem, i'm posting it here:
i replaced a pump motor a couple weeks ago (hayward maxflo 1hp) cuz the bearings were squealing. but since then a mysterious problem has persisted: the system won't come up to pressure as in the pump doesn't seem to be moving the volume of water it's supposed to. i checked the impeller and it's on tight (did replace it a couple years ago), and it doesn't seem anything is obstructing the suction or discharge side. i went out to troubleshoot, and after taking the pump apart 'n putting it back together to test it three times, it finally all worked just fine. the only variable is possibly the diffuser gasket had gotten incorrectly positioned but was corrected the last time. but now a week later, the customer has called to report that once again, after functioning well for a week, the pump is again not bringing the system up to pressure.
thanks for any suggestions!!