That makes sense, it sounds as if your plug had caked itself up with some more or less conductive crud over the years. It also explains why you got poor results holding it against the engine, but good ones with a decent plug even though that one was gapped to 0.060" instead of 0.025". A ring and valve job in spring-time will probably make it behave like a new engine. If it doesn't, adding in a carburetor clean is just about sure to.
Thank you for posting the answer to the problem MacCullum - that makes this a useful archive. I'll now close the thread: if anyone needs to add to it, just send a PM to a moderator.
