Dallman,
I think the issue here is how does the {heat--moisture--smoke} vent out during the cooking process. Leaving the door open after cleaning has no effect on what may have really caused the problem in the first place.
If you had no vent, the gasses & moisture had no other escape than through the cutout for the generator. Hence lots of gunk.
Preferably you have a top vent, (Heat rises & so does the moisture & crap encapsulated in it.) and smoke should not be escaping through the generator except for the odd wind gust.
Hope that helps & I'm glad Bradley got you a new one. I'm not so sure they'll do #3 though.
Kirk
http://www.chezbubba.com Ya think next time I check into a hotel & they ask "Smoking or Non?" they would mind?