I have an older Merc outboard that has always been fairly reliable but
went to start it the other day and it appears to have no spark. I've
checked the kill switch circuit and it appears to be OK. It has an
electronic ignition module on the side of the block which gets two
inputs from the vicinity of the flywheel and sends its output to the
coils next to the sparkplug wires.

Anybody have an idea how to troubleshoot it from here ?