Recently rebuilt a Zana Model H31c-63p carb. because the unit suddenly had no power. Now the plug fires but the engine will not attempt to start even with a dose of engine starter spray.

Hi,
Wrong Zama number; but your muffler is plugged. If round pipe; #2 phillips screwdriver in it. If not there, 5/16" socket and open muffler and remove screen.
Peace,
Clarke