Looking at the photo (with the worklight)---that silver DUCT must be removed to gain access to the BLOWER WHEEL for inspection.
Remove the LINT FILTER & place it inside the drum
Remove the 3 screws which secure the *silver* DUCT
Pull the DUCT down & towards you
Inspect BLOWER WHEEL for sock/fabric softener sheet etc.
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Yes---the amount of dust indicates *poor venting*
Usually caused by an excessively long-length vent system (much longer than 8 feet)---but can also be a shorter length vent with *too many* 90 degree turns----or a normal-length vent system that is blocked/restricted somewhere between the vent behind the dryer and the outside vent hood of the home/house.
Many customers/owners will say that---yes---when the dryer *was* working---it took a long time to dry clothing.
With heavier fabrics (denims/towels)---the cycle would end and clothing would still be damp-to-somewhat-wet(poor venting).
Great pictures
Edited by john63, 15 December 2011 - 12:36 PM.