Thermostatic radiator valve not working

[SRJDIY]

Hi, apologies if this is a daft question, but the valve on one of my radiators doesn't seem to be working.

The dial turns fine, but turning it doesn't turn the temperature of the radiator down. I've tested it by touching the radiator, then turning the dial and waiting an hour before touching it again, at which point it feels the same as it did before. The other radiators in my house look like they use the same type of valve; I've tested one of them the same way and it works fine.

Does anyone know what might be happening please? I've attached a picture if that helps.

[dewaltdisney]

what often happens is that the valve pin can get stuck. If you are lucky you can remove the top you can tap it and free it off. This will save a thousand words https://www.youtube.com/watch?v=dwh3-JSQxWw

DWD