i.e. when the Schrader valve core fails most likely due to old age. Correct (fuel resistant) replacement cores are available from oldcolemanparts.com I've heard tell that schrader valve cores as used in air conditioner units are also suitable. Schrader Valve - Dimensions http://www.sunairindustrial.com/catalogs/valves_cores.pdf From memory, a new valve core in a 275 must be adjusted so that the control functions correctly so it may be an idea to count the number of turns when removing the old one. Check that the valve opens only when it is supposed to be open and most importantly, it shuts when it is supposed to be shut preferably before adding fuel and definitely before even thinking about approaching the lantern with a naked flame. Again from memory, the 275A was designed a little differently, just screw the replacement core all the way in and you're good to go. I'm happy to be corrected if I've got this last part wrong.
