Thanks Brian.
No, the plastic cover is not tight and rotates under normal tension Off to Full.
I'm assuming that the pin mentioned in other threads is part of the thermostat section and presses onto a seperate piston within the brass valve section which actually shuts off the flow. If correct then I'm guessing that the piston is damaged or debris is trapped at the closure point.
Think I'll need to go down the full replacement route.
Manch
Manch
February 2011