Water not flowing through radiator??

[olibill]

Hi, I have an oldish CH system, which I had power flushed a couple of years ago.
This week, I have had to go round and free up the TRV pins which had become stuck down. However, on a couple while that has brought the hot water up the pipe to the TRV, the radiator is only slightly warm, at the top.
The pipe on the other side of the lock valve is cold. This may be a stupid question but is this a lock valve problem? If so, I cannot get the plastic head off to adjust it! I have taken a photo of the lock valve in case that helps. I would be really grateful for anyone's advice.
Thanks very much.

 

[exedon2]

That's actually a wheel head valve so should turn ,if its stuck the head just pulls of or may need a gentle tap.
Its possible trv pin needs to be persuaded to move some more
If that fails turn off all rads that are working to force circulation round the non working rads

 

[olibill]

Thank you very much. I'll try that!

That's actually a wheel head valve so should turn ,if its stuck the head just pulls of or may need a gentle tap.
Its possible trv pin needs to be persuaded to move some more
If that fails turn off all rads that are working to force circulation round the non working rads