soundmotor
super modified
One other thought, FWIW...
Do you have a 'critter shield' (plastic or metal screening) on the outlet (outside) of the vent? We did, and that sucka clogged up nearly solid after the first few months of use.
We discovered it because the dryer -- wasn't drying.
We're lucky we didn't have a fire.
We removed the screen -- so far, no problems with clogging nor with critters (fortunately).
No, aluminum flapper door.