What is the diameter of the "gasket" material you need? If I understand
correctly, you need the stuff that fits into a groove in the bronze
casting, around the perimeter of the glass. There is round, vinyl
material called "spline" that is available in a number of diameters as
used in window screens, storm windows, etc. Home Depot and Lowes have it
in three or four sizes from about 1/8 inch to around 3/16 inch diameter.
I believe window screen/storm window shops have it in a greater range of
diameters.

FWIW,
Ed

Chuck Baier wrote:
I am looking for a source for ROUND gaskets for my bronze ports. I
have found the square ones at Defender but the grooves in the ports
are round and the square ones don't seat well no matter what I do. Any
sources will be appreciated. Chuck