repeated tumble dryer overheats. different models, ways to avoid?

I have owned 4 tumble dryers in a row, all have overheated on between 1st and 3rd use. Im wondering what I can do to avoid this?

They are in the kitchen under the work surface, with 2cm clearance on sides and top, about 6-7 cm at back, and a unkinked vent pipe, room is a average temp with no heating on. Any advice?