In reply to rallymania:
Fixing these stoves is almost always possible, and generally worthwhile.
The folks over at
http://www.spiritburner.com are probably good people to ask for advice. There are a couple of guys there who manufacture and sell spares as well.
I got a bunch of spare o-rings, NRV pips etc from one of them a while ago.
On the not blowing yourself up front, just do it at the bottom of the garden at arms length. They have a hight tech emergency overheat valve in the filler cap (in the form of a blob of solder), so the worst that is likely to happen is a jet of flame from the fuel tank.
Post edited at 22:55