I have a very long dryer vent run that is about 18' or so, and is completely behind a wall. Included below is a rough sketch of what I think the vent looks like, but I have no way to confirm that without removing a lot of dry wall and flooring.
I bought one of those dryer vent cleaning kits that has a brush on one end, and has a bunch of attachable rods that end up attaching to a drill. Unfortunately if I come at it from inside the house (basement), I think it's getting caught up on the second 90 degree turn right before the 11' stretch. I tried coming at it from the outside, and I think it's getting caught up again on the 90 degree turn right before the 11' stretch.
I took a rigid shop vac that converts into a blower and blew at the vent from inside the house, but that basically did nothing (in fact, the vent flaps on the outside vent cover didn't even move / open).
What do you guys recommend that I do? Should I just leave it? The dryer runs fine, I just wanted to clean the vent as that's a potential fire hazard.