Ok what I think has happened is the door that you believe to be causing the air to leak into the freezer, thus causeing the frosting/iceing is not your problem.
Please click here and locate part #23. This is the chute that leads down to part #9 (the door) in this drawing.
Now you think that the problem is where these two meet. ie: door and chute.
Please excuse me, but I must disagree for the following reasons;
I believe that when you pushed up on the dispenser door or whatever (yes, I saw your post over at The Masters' site. All praise the Sacred Brew.) you dislodged part #23. This in turn causes part #9 to move forward because it is still attached to part #12 in the second link, This in turn makes the door open just a bit.
The combined leaks of the chute being out of alignment and the door being ajar causes the problem you have.
So... What to do to fix it. First take the door assembly (#9 second link) back out. Then you can align the chute properly. You will probably need to glue it with something. 3M weather strip adhesive works great for doing this. Scuff the plastic with some sand paper before you apply the adhesive. You can get the adhesive at any auto parts house.
Once you get the chute back where it is supposed to be then re install the door and motor thingy. Have someone shine a flash light down into the chute and see if you can see any light getting past the door.
FYI the door is opened by the lever (#24 second link) when you push on the pad with the glass. If it isnt opening it is because the upper most part of the lever is not connected to the door. The only thing that the "door motor" (#12 second link) does is like those hydraulic screen door closers do. It keeps the door from slamming closed and then applies a bit of pressure to keep it sealed tight. It does not open the door.
I was hoping to be able to provide you with detailed repair instructions from a service manual, but the only thing that is in it that is specificly about the chute or door is one measley line of text. Everything above I had to figure out myself.
So if it is wrong blame the manufacturers for not providing decent information.
If it is right ....Well just call me Mr. Genious.......(just kidding )
Please let me know if you have any other questions ok.
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