I too have experienced the problem you are having with my
Ventus which was manufactured in 2004. It took me a long
time to figure out what was wrong. Eventually I simply
worked my way through the system to discover that
everything free as it should be except for the master cylinder
plunger which was frozen in the body of the housing. I
removed the unit, withdrew the actuating plunger, cleaned it
and then put silicone grease on it. That was the fix! Now I
will grease it every year at the annual…

John Sullivan, UFO