The problem was a non-usable dryer vent. More than just a cleaning. The old non-code vent line essentially had disintegrated. Dan and Oscar completely re-constructed the dryer vent from utility room to the exterior wall -- including some tight twists and turns. Minimal wall-surgery required. Very well done, and they cleaned up the work area. A fair price given the scope of the project. I finally have found my choice for HVAC service, repairs, and replacements.