Abstract: A monitoring system for a rotating diverter head for use in the drilling of oil, gas and geothermal wells. The system includes a pressure sensor which is mounted beside the stripper rubber which contacts the drill pipe. An increase in the pressure monitored provides early warning of degradation or imminent failure of the seal. Apparatus and method are also described for the system with a head having dual stripper rubbers. Additionally a support for locating a housing of the head is provided so that the stripper rubbers can be replaced on-site.