When i took te motor apart I made sure to place everything back how they should be. When I had the front cover off I saw that when I turned the shaft the spring hanger jumped back and forth normally, so I don't really know why it doesn't work with the vacuum on.
Possibly there's something in the motor itself that prevents the vane from going far enough to make the valve switch positions. If the wiper on the vane is displaced to one side, that might be it. I'd try a little bit of lube on the switch. You can't make it worse.
