Dryer vent cleaning through attic. Roof has a steep Sloan and 4†dryer exhaust vent is venting from an 8†attic air vent, instead of a 4†dryer dampered vent. Recommend having a roofer place the proper type of vent. Inspect vent with camera and after inspecting attic space found that vent is approximately 28 feet in length with 5 turns, and is completely backed up throughout. Cleaned from below with 8 passes and from above in attic crawlspace with 3 passes. Cleaned up excess debris, Reconnected vent by strapping to attic air opening and reconnect new dryer and cycled system on to ensure proper operation. Dryer is operating well at this time.