Yes the originals had a gasket. That's probably why the replacement band is fitting loosely. Most FLAPS worthy of the name have gasket paper on rolls in about 3 different thicknesses. Use whichever one takes up the gap best.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!