We have a 10 year Kenmore Dryer. Last year we notice it wasn't drying as well as it usually does. We pulled it out and vacuumed the back of dryer and the dryer vent hose. But that didn't help much. After a lot of research we discovered we hadn't cleaned the vent outlet that leads out the roof in all this time. After cleaning the vent the dryer worked great again - but only for about 10 loads and then the outside vent was plugged again. Over the past 3 month we have had to clean the outside lint vent at least once a month. There is always build up but after cleaning outside vent, dryer is good again. Not sure what might be causing this build up since we never had to clean it for about 10 years. I have always cleaned the lint trap after every load. The lint trap seems to work good - it always has some degree of lint in it depending on what I am drying. Was wondering if it has something to do with the vent hose after we reconnected the dryer after cleaning the back of the unit. I am kind of at a loss - husband wants to buy a new dryer. But I am afraid we will have the same problem if it is a vent issue and not dryer problem.