It's good to hear about manufacturers that work with their customers to fix problems.

The odd behaviour of that particular model of FID might actually provide input to general design improvements; the early GCs had a whole range of FID chimney, jet and collector arrangements that all worked well enough (with the packed columns of the day), with ne really clear differences in prerformance that could be used to fine tune the designs. As far as I know there is nothing in the literature to show that, say, a Varian FID design was better than say an Agilent, although I am sure that the manufacturers must have done some development testing.

Peter