I bought a Lister bale elevator off a local farmer which hadn't a run since the 70s, I checked for a spark, nothing, removed the flywheel, cleaned and gapped the points, refitted flywheel, No Spark. I then purchased a secondhand Briggs & Stratton Electronic coil off ebay, and fitted it, which is easy as you don't have to remove the flywheel, and away we went, huge blue spark, I then clean out the old petrol tank, fuelled up and away it went after 40 years!