Danfoss Radiator Thermostat Adjustment/Repair?

Tweaking the pin generally works for me but this time there seems to be an additional problem. When the thermostat is replaced, it turns off the pin valve mechanism. Once removed, when twisting the thermostat setting, the plunger which controls the pin doesn't seem to be moving and I assume it is stuck in the wrong position so that it depresses the pin and shuts of the water when the thermostat is replaced! The position of the thermostat ie the number displayed doesn't seem to have any effect. Any ideas? Thanks