My Whirlpool dryer M#LER4634EQ2 is not drying on the Perm Press cycle but does dry on the high load cycyle

Driers will do that when the lint builds up like concrete on the inside of the air ducts and the lubrication dries up, plus you have a safety that is opening and closing when it cools down. It's so full of dirt the next thing it will do is to catch on fire and burn down your house. Also, the sensors get blocked from sensing when the dryer is dirty and that is your problem now, in fact, the sensors could even be bad. If your dryer has thermistors then you will have to test them with a thermometer and a good digital multimeter. It's pretty easy to do as you just measure the resistance of the sensor while testing the temperature, too. You can do it with hot water. Most of the time just cleaning it well with soap and water cures the problems and makes it run like new. You also have a hi-limit safety. The safety is behind the drum, but NEVER install a safety without first thoroughly cleaning every part of the dryer. You need to totally tear it down and scrape out and wash all of the parts except the motor, which you vacuum out. You have to totally tear it down piece by piece. Halfway cleaning it will not work because all it takes is one clogged up air passage or dirty sensor. You can go to YouTube to see videos on how to take it apart, but do a very good job or it will fail again quickly. I would get a new belt and change it while you have it apart and get some white lithium grease and grease any bearings you find. The support rollers are greased by pulling the pin and greasing it and greasing the inside of the roller. You need to clean out a drier every two years, at least, according to the manual. You just unplug the wires from the sensors and remove ductwork that they are attached on and clean the entire thing with soap and water. Make sure you go all through the dryer and get all parts like the blower fan and housing (it has to be scrubbed and washed out), vacuum out motor well and clean exhaust. Mark all wires you unplug so you know where they go. If you leave any dirt in the ducts it will blow another fuse quickly or will not maintain the temperature correctly. This is an easier job than you would think. Make sure to clean around all of the sensors, if it has them. Also, change the belt while you have it torn down so you won't be doing it later. See: Dryer vent cleaning prevents fires - YouTube (http://www.youtube.com/watch?v=A6wmD502-xE) and: Cleaning out a dryer with top lint cleanout - YouTube (http://www.youtube.com/watch?v=OBNDbyRm68M&feature=fvsr)
Cleaning out a dryer: By a woman 2 of 2 - YouTube (http://www.youtube.com/watch?v=a73HTFkcB90&feature=relmfu)
Manuals to download:
https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20Dryers.zip
https://dl.dropboxusercontent.com/u/8010163/Whirlpool_Thermal_Cutout.pdf
https://dl.dropboxusercontent.com/u/8010163/How%20to%20use%20Test%20Equipment%20Service%20Manu al.pdf
https://dl.dropboxusercontent.com/u/8010163/Electrical%20Theory%20and%20Diagnosis%20of%20Major %20Appliances%20Service%20Manual.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool%208178584%20Cabrio%20Dryer%20Service%20M anual.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20Dryer%20Mechanical%20Systems_Basic_How _to_book.pdf