It's probably old enough to be a breaker-point system, so the process to fix an ignition fault is straightforward: check coil to flywheel gap, clean points, correct breaker gap and timing, check coil primary and secondary for open circuit, check wiring, and if it's none of those, try a different capacitor, then a different coil. Once you've found the fault, you can start the difficult part: finding a replacement part that looks like the original one.
If you need something like crankshaft seals or a new piston, you may be in trouble.
