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

Bonjour Tony,
Many thanks for your accurate reply.
Your M90 runs quite well gently, and we can actually hear its hit & miss process. I thought mine is a little bit too slow because I do not hear the hit & miss process like your one.
Never mind, as it runs, I do not touch to anything now, especially the plug because I agree with you, not obvious to find another one if I break it.