If it won't crank, it's either the starter switch itself which may have pitted contacts, or possibly the linkage from the pedal to the starter switch. I'm assuming it has the stock stomp starter.
It could also be the starter needing rebuilding. If it lands on a bad spot on the commutator, it may not spin up.
I don't believe it would be the ignition switch, unless someone has converted it to a key operated starter with solenoid.
