The PSL PMC model controls a PSL shutter via ezcawrites to the EPICS record H1:PSL-EPICSALARM which runs on the Beckhoff IOC/OPC in the diode room. It was discovered that the shutter was being driven closed. We tried reading the status of H1:PSL-EPICSALARM using caget on the OPS and H1FE LAN, but did not get a value. Later we found that caget does not work with this PV, but PROBE and EDCU are able to give its value. This slowed up our investigation slightly. Looking at the MIS part of the PMC model, we found that the coolant flow is in range, but the FLOW_OK was latched bad. We pressed the FLOW_ERR_RESET button, and the FLOW_OK came good and the shutter opened. Trending H1:PSL-EPICSALARM shows it transitioning from ONE to ZERO at this time.