heater valve inop?

[TomM]

I have the same controls and when mine was doing that, the cable was binding which would spring the knob back. We lubed the cables and that fixed it. Mine was also on the pilot side......

If you look near the rudder pedals, you will see where the cable goes as the divider box is on the inside of the firewall.

Its just one of those chincy solid metal wire in a spiral wound metal outer housing and I do not believe there is a liner in there at all. So when you get some corrosion along with no movement, it sticks. Basically the same cable as the throttle on a lawn mower.........except with a much higher price tag.

After rereading your post, yours does the opposite of mine....It would snap closed again due to binding. Still may be the cable though