Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hard to say how long the O-rings may last. It seems to be the consensus that only one is needed, so you automatically have a spare right there.

I have broken a spark plug myself, which I found to be very easy to do by mis-aligning a slightly oversize long socket, and putting a little torque on it. They are rather delicate me thinks!!!

Properly handled, they'll probably last a lifetime though, I just screwed up!

Still, it probably is best to have a spare around, just as a bit of Murphy prevention if nothing else!??!  ;c)