Problem solved- the float was a little cocked so the toe-of the-float float level reading was off. No gushing now. Sometimes the time to write a question here gives the mental space to try again. Maybe the too high float contributed to last years monster backfire.
Dave
In a different lifetime, when I was a computer systems programmer, and had a code problem that just had me totally stumped; I used to call in someone that knew absolutely nothing about programming, and go through the code explaining the code as I went. Generally, it took about 15 minutes or less to find the gremlin.
Jon.