Hi, I have one radiator out of 12 in my evohome system that doesn't seem to be closing so the room is overshooting. It's one of these which I'm struggling to identify:


I've changed the Hr92 to Stroke 1 mode and made sure it's screwed on tightly.

I planned to try screwing the pin part down a bit but it's an 8 sided fitting and seems to fall between my 10mm and 11mm sockets in my socket set and I don't want to mess it up with pliers if it's not going to help?

Any advice gratefully received!