Solved - replaced driver footwell flasher with O'Reily's off the shelf EP35 flasher. Chased grounds, etc to no avail. The replacement package says "LED Compatible" - my bulbs are incandescent. The Tridon piece it replaced said "failure indicator". So I'm kind of cheating since the Tridon product sensed a failure somewhere (all bulbs working). The off the shelf version is evidently electronic and is not amperage dependent. So there may be a gremlin somewhere, but the fast blink is solved.
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