Try popping the flywheel cover off to make sure a pickup coil hasn't vibrated loose, it happened to me.

One of the small Allen screws had dropped out and had been magnetically "sucked" in behind the flywheel. It lodged in between to of the stator coils and burned the stator out, causing IGN failure!

How did the motor stop? Was it a sudden failure, or did performance seem to break down over a (short) period of time? Also, are you positive there is no spark from either plug? The spark can appear very weak when the plug is out of the chamber, but is actually sound!

Andy.
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