Don, I managed to leave my ignition switch on for several days...yep, I am definately getting older!
I returned to the boat and after discovering I left the switch "on" (my on- board charger kept the batteries charged) attempted to start the motor. Normally it started on the first turn of the engine but after 3 tries concluded I must have damaged either the ignition module and/or the Pertronix Flame Thrower coil.
I replaced the ignition module as routine and then checked for spark - it appears orange couloured and weak and the motor still won't start. Fuel is flowing to the carb and I am getting a nice fuel vapor from the plug holes if I rotate the motor with the fuel tap on. (Something I don't do for long after having a similar experience with my 1975 Norton Commando where I started a beautiful fire at the plug hole whilst testing for a spark!)
Any thoughts on whether it is time for a new coil?
PS - I think my description as a "senior member" particularly appropriate at this time!