I have a craftsman lawn tractor with an 18HP Kohler twin, model M18S.
Twice now it has failed to start due to no spark. By the time I fiddle
with ignition switch and safety switch to see if something is not making
contact, it mysteriously starts. I would say in my experience with other
small engines the spark intensity looks weak.

My question is about the ignition unit. Does anyone know if these are
prone to this type of intermittent failure as they get older (13 years)?
Is there some way to diagnose this other than stick a screwdriver in
the sparkplug wire to see if there's a visible spark? I hate to drop a
bundle on this module if it's not the problem.

If there's a better forum that specializes in small engine repair please
let me know, but I saw a fair number of posts on mower engines on
these groups.
thanks