You should be able to feel play in the hinge after 1,000 hours. Expect door wear too.
I replaced hinge with baffle rubber and fabricated new door. It's showing wear again one thousand hours later![]()
Me too, and ditto! My carb heat door is currently in real need of replacement.
Green gunk is most likely fule dye, probably would be a good idea to blow it out.
I ended all the issues with the wire Push Pull cable by going to a cable with a threaded end. I use a rod end fitting. No Mickey Mouse issues. This is an important control and this isn't a place compramise.