I have found though that the S410 seems to have developed a leak in the valve (old style ball rather than the newer T bar) in particularly cold weather.
The first time this happened I wondered what the noise was before I realised it was air whistling out the end of the cap....
Was out last night on rat patrol, and the dreaded sound started up again


So the question: do I replace the old style vale with the same (assuming I can still get hold of one) or do I replace it with the newer valve? Is that even possible?
It has never done this before so I guess it is down to wear on the valve with time?
cheers
Dave