mercury 60 3 cyl no spark

[chrisparry]

Hi all, I have a Mercury 60 3 cylinder 1998. Has never missed a beat for 24 years, but cut out last week and not started since. No spark on any of the 3 plugs but engine cranking healthily on the key. Gone through as much tests as I can but not sure how to test the stator (read this may be a cause on previous thread) or how to test the CDI/switch box. Thanks