I've noticed a drip coming from a c/h radiator valve connection, and I'm not quite sure exactly what I'm dealing with. Here's a pictu http://tinypic.com/r/fegh85/8

Having Googled around I think there's an adjustable radiator valve tail extension. I'm not sure though, I've never fitted one myself.

The drip appears to be coming from where the adjustable valve tail narrows. The drip seems to be unaffected by the tension of the nut, but does seem to slow if I lift the radiator up.

It's all a bit horrible, with some awkward boxed-in pipework (not me).

Is there a right way to fix this, or a quick way please?