In the course of doing some repairs inside my clothes dryer I stumbled across something I should have known. At the back of the dryer is the port for hot air to exit, connected to a vent hose that goes outside. In my case I put a 90-degree 4" duct elbow right there, then a flex hose up to the vent pipe through the wall. Now, I'm used to cleaning lint out of the vent pipe a couple times a year. But while inside the dryer I disconnected the venting ductwork just where the elbow is mounted, and found it more than half blocked with a hard pack of lint. In retrospect I certainly should have known that a right-angle turn is a likely trouble spot for accumulation of lint, but I just never thought to check for it. From now on I will. If you haven't, check you own - blockage anywhere in the vent will slow your drying and cost you money!