We have a Kenmore Elite Dryer HE4 Smart Heat / QuietPak9 M/N - 110.c85088400.

It is about 2.5 years old. The filter is clean and fine. The Exhaust venting is clean and fine. However recently the dryer starts beeping a "clean filter" warning about 5 minutes after starting, suggesting to me that there may be an accumulation of lint inside the "Dryer Cabinet". How does one get the "cabinet" open to clean inside?

Parts breakdown should be here: www.searspartsdirect.com

See if that helps.

Also check for obstructions in the exterior venting. Animals like to nest in the duct work.