I have the above problem with my 1963. The effect is the chronograph resets itself when I press stop. I think the actual problem may be the button itself is a bit stiff and putting up too much resistance for the puny spring which pushes back on the reset lever - the button needs a firm press to engage then returns slowly after pressing). I can manually engage the lever directly on the movement, making the chronograph reliable. But when I reset, the lever just returns maybe half the distance it should. Does anyone know how I can loosen or grease the reset button before I start looking at the spring?
Thanks!