accessing the pin in danfoss thermostat

[alba]

I have a cold radiator and am assuming that the thermostat pin may require releasing.
Unfortunately I cannot work out how to remove the outer casing to access this pin.
I think its an older model, but the description is as follows ; black cap on end with danfoss logo, the main part is white plastic which flairs into a skirt shape at the bottom where the numbers are printed. Beyond this is a black plastic ring with a small pointer which superimposes over the number skirt.
Hope this is an adequate description....the point is I can see no screws or apparent means to release the sensor cover and gain access to the pin.
Don.t want to force anything but is it just clip-on? If so what do I hold and what do I pull.
Would be very grateful for advice or input. As a pensioner I can,t afford to pay out £60 for a two minute job if can avoid it.

Excuse rambling post

Thanks in advance

[htg engineer]

Where the numbers are printed, or maybe just below. This will be where it is connected to the valve. You should be able to turn a part of the valve by hand to release it from the valve.

It's normally a large nut that is just tightened on by hand.

You may need waterpump pliers or something similar if the valves are quite old.

[The Heating Doctor]

Some Danfoss TRV heads are attached to the valve body via a collar with a allan key, once the allan key is released then the head can be removed as described by htg eng.