Hi guys: I was able to take the venturi out of the car to the bench. I found out that the flap is sticking at the shaft on both sides. There are 2 slave type bearing on each side covered with an O ring and a washer (see pics). The flap was hard to turn even with fingers. I cleaned up the venturi with solvents and overnight soaking, which did not help. It turned out that a deposit and accumulation of materials were covering that part of the venturi interior surface for over almost 60 years of use. So, I did a drastic cleaning method by using 2 fine files, one is an oval shape, and the other is triangular. I filed the wall of the venture where the flap touches using both files and experimenting by moving the flap by finger. I also filed the edges of the flap. I emphasized on the area where the flap touches the wall, particularly, at the shaft corner on both sides. With hours of arduous work, the movement started to improve. I kept going and filing the rest of the wall area, the movement eased up to a point that the original spring can return the linkages easily. When I assembled the venturi back in the car, the measurements of the linkages had changed slightly. I started the car, the flap was fully closed, it ran well, the flap did not stick even when fully closed. I performed the linkages tour, and it checked out fine. I adjusted the air screw using a vacuum gauge which gave the maximum vacuum reading. Now all is well, the original spring is the correct spring.
