personally I'd freeze the pipework either side of the rad. but this is costly albeit quick.If it's damaging a good carpet you'd best do something sharpish.
Bank on £75 for the freeze plus £20 or so for the valves(both should be replaced).
Merry Christmas.
George Anderson
December 2007
The only satisfactory way is to replace the valve itself, unfortunately which will involve depressurising the system and draining the radiator in question. Very few radiator valves are dismantlable these days - some early ones had a gland spindle nut that you could undo and wind some PTFE tape in.
John
December 2007
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix plumbing.