There have been some interesting posts here.
The vent pipe in your wall should be rigid metal, so a wire brush
should not harm it.
If it is flexible of any material, replace it.

If you use a shop vac on "blow", then be sure to use it from the
inside of your home.

Be sure to clean the inside of the dryer vent termination cap on your
roof. Quite often, that is the source of the blockage.

Modern dryers are rated to push air through at least 25' of dryer
vent. Be sure to deduct 5' for each 90 degree elbow.

Good luck with this project.

Alisa
Certified Dryer Exhaust Technician
http://CleanYourOwnDryerVent.com