The handy dandy dryer repairman has been here twice now, and we may have the problem fixed. We think it was the vent on the outside of the house. Now this is strange. I check it every so often to clean the lint out, and this was a new vent @ 3 years ago, to match the siding. (we were doing a little sprucing up) Well it's plastic or vinyl or something nonmetallic, and it seems like after you do a couple of loads in a row, that it gets warm and soft, and the little flapper that is supposed to be pushed out by the force of the air blowing thru, just kind of melts back down, and closes up the vent more than halfway. Causing backpressure. Then the thermostat won't let the dryer heat back up etc. etc. and my clothes don't get dry! So he replaced the vent, and we'll see if that helps. Boy, if there is a dumb thing that can go wrong with anything, it will happen here! And it only cost me $91 and three visits to figure this out! So cross your fingers.