I picked an old pair of Buell Strombos air horns. While cleaning them
up I took the back cover off and noted someone had used clear silicon
as a gasket. I see that there is a gasket for these horn (about
$0.75), but am not sure the order to assemble the horns with the
gasket. My assumption would be:

Horn -- Diaphragm -- Gasket -- Back cover plate

Does someone know the proper order to reassemble these?

Thank you
-al-