Re: Please Help, No Spark!!!
Disconnect the rectifier and test for spark again.
The purpose of the rectifier is to charge the battery. The motor will run just fine without it, but a blown rectifier can (sometimes but not usually) ground out the ignition. Don't ask me why though - I'm pretty much a hacker when it comes to electronics - I assume it has to do with feedback or something, and the diodes failing open/short in the right (wrong?) configuration.
Some causes of rectifier failure: battery hooked up bassackwards, loose battery connections, excessive corrosion on battery terminals, battery cables rusted through, battery disconnected with engine running, engine rope-started with no battery installed. I have heard rumors that the 35-amp water-cooled rectifier/regulators can be smoked by jumpstarting the motor from another battery and by connecting a charger to the battery without first disconnecting it from the motor, but I don't believe those.
Anyway, still no spark - I'd go with the best info you have (timer base leads out of spec) and proceed with replacing the timer base - but I'd take the flywheel off & inspect the magnets before ordering parts. Just make sure all the magnets are glued firmly in place & haven't shifted or anything. Also inspect all the wiring for obvious faults (pinched wires, chafed insulation, burn marks, that sorta thing). disclaimer: I'm not a mechanic, just a determined do-it-yourselfer with more time than money to spend on boats.
good luck.