I purchased my mower new in 1975 and it was used regularly for over 20 years. It then languished at the back of the garage for a number of years until a renovation of my garden required better defined stripes on the lawn. Other than replacement of one cylinder bearing, it has served me well until a few months ago when the engine stopped while I was mowing the grass. Not seized, just stopped. I assumed a blockage in the carburetor so cleaned that out, to no avail. On having it checked, I was advised that the spark was weak and intermittent so I have replaced the coil/condenser assembly in the magneto. I now have a decent reliable spark but the engine still does not fire. On removing the plug I can see traces of and smell fuel. Can anyone advise what I should do next ?