It seems like is a poor design, the lint filter is just a couple inches from the bottom of the drum , the clothes are constantly on top of the filter causing a poor air flow. before you buy a board or any other part , try to raise the front legs as much as possible so the clothes will stay away from the filter, im doing my fifth load now with no problems.
I am a tech and i tested everything before doing this. good luck people!
I will also recommend to buy a new lint filter, that will definitely help. don't spend any money cleaning your vent or doing any modifications to your vent exhaust .
Product or Service Mentioned: Kenmore Dryer.
Reason of review: Bad quality.