If it is taking over two hours for your clothes to dry I recommend you not turn your dryer to high, set it for forty-five minutes and leave the house. After calling the dryer vent guy we now know why no air was getting through the vent. A rather large birds nest, complete with at least six eggs, was removed. Drying time, for a full load of laundry, is back down to thirty five minutes. Feeling rather thankful I didn't burn the house down.