When you move your weight by hand to open and close the flapper, is there any resistance at all?

With or without the spring attached on mine, there is no resistance at all to the flapper movement.

At rest cold, the weight sits fully at the bottom of its travel.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)