I was able to confirm dpmahon's theory that the interruption of ink flow is caused by a gap between nib and feed system, which interrups capillary action.
To prove that, I re-inked the pen and wrote past the skipping stage until the nib refused to write altogether. Then I inverted the pen (as if I were to write with the back side of the nib), and pushed the nib against the paper until the nib flexed and made contact with the feed system. Almost immediately I saw a tiny spot of ink on the paper. Then I turned the pen around and started to write normally.
I've repeated this cycle a half dozen times since refilling the pen, and every time I was able to get the dry nib to start writing again.
The gap is a flaw in the feed system of my pen, and I'm guessing it's caused by poor assembly or poor selection of materials. Anybody else with this problem?
Aldo