I discovered while attempting to replace CP8's magnehelic diff. pressure (mechanical level gauge) gauge that the recent reboot/overpressure episodes had caused a previously unnoticed soft rubber plug to pop out of the back of the gauge.  I reinstalled this plug and now the gauge is working normally and won't requre replacement.  Obviously, this device is designed to pop out and prevent damage to the measuring diaphram in the event of overpressure.