What is the vent material made from? If it is anything other than rigid, flat metal, have it replaced. Any of the corrugated material (either Nylon or metal) will result in loss of air flow and lint build up which could pose a fire hazard.
BTW. Whom did you have inspect a dryer vent? I have heard of some pretty poor cleaning jobs done by chimney sweeps and the like. I'm not saying that they are all bad but probably best to have a trained appliance service technician look into it as they will know if the dryer is functioning properly afterward or not.
But anyway... you can see one dryer vent booster at the following link: