Hi Norm,
Sorry to hear that. It could even be OK by the time it gets to you after a ride in the car. I wonder if there is some foreign matter in the seat. I only work on my own family's mowers but I can understand how frustrating it would be to have this happen on customers machines. Of the two problems flooding is at least easy to see.
Its just that when they do work these carbys work so well, particularly with your modifications. Strangely a few of the really old original Victa plastic needles seem to be OK. If they work I leave them alone.
All the best
Jeff