Have opened up the Mayfair. Put a compression gauge on the spark plug hole, it read 0 not matter what I did. There was a wire not connected which I connected to an electrical lug that seemed to have a wire missing, still no spark though when I checked for a spark against the body of the mower. The decompressor is tight in its bore but I notice it has a slight wobble when I touch it, not sure how important that is. It is a Series 70 mower.