Thankyou for the reply, Brianf, is muchly appreciated.
On further tinkering, it would appear that the unit that broke its moorings was actually the coil assembly. It seems to be okay on testing with a multimeter (11.67 kOhms from spark plug cap to either terminal, 0.00 ohms between terminals, again correct me if I'm misguided!), which leaves spark plug (replaced) or CDI, which I'm at a loss as to how to test.
Again, thanks for the input, even though my machine's not exactly a moped in the classical sense of the word.