I received the new main jet and measured the hole diameter using a sewing needle that just barely fit and the size was .042". When I removed the old main jet and measured the hole size it was .053". I looked at the old jet with a jeweler's loop and did not see any sign of corrosion
even though the hole had enlarged enough to be obvious with the naked eye. Don't know why it happened, but the old jet had eroded and made the mixture too rich. The small holes in the venturi tube above the main jet and small holes in the low speed jet were also slightly larger than the new parts
I ordered, but the primary culprit was the enlarged main jet.
The Admiral and I tested the engine
yesterday and the dink jumped out of the hole and developed full power. Wide open throttle was very smooth with no "missing" indications.