Kind of an old thread but...
It sounds like your prime valve may be bad. The part ranges from 35-85 $ depending upon how crafty you are at shopping around.
If it was stuck the other way I would make the assessment that your packings are in need of being repacked and a slight tap of a hammer...
Remove the loose stuff and anything that will contaminate your mud, big gaps should be prefilled, might want to drive some screws into the boards to make sure everything is nice and tight. I would stay clear of mesh for the corners as it does not crease into a nice line like the paper does. tape...
Hello, my name is Sean and I am a professional paint contractor in the Huntsville area. I participate on many forums and thought this looked like a nice site to post on.
I paint garage doors all the time with a quality exterior paint. Clean, scuff and paint, as you raise the door you will get into the cracks and the edge sealed area.
I agree with this post.
About the door remove any failing urethane and reseal. If it does not restore it back to satisfaction you may have to have door regrained.