The dust monitor at the H1 PSL (location 10) (S/N 980500276) alarmed with something like 'sensor fail'. I have replaced it with S/N 000800169. Neither have internal pumps. I put the temperature and humidity sensor from the old one on the replacement.

The alarm severity settings were not set for any of the dust monitors. They were probably lost with the last power outage. I have set them now.