[gman357]

My dryer works &heats up for about twenty minutes, then stops before the cycle is over. When I push the start button it makes a buzzing sound, if I repeatly push the button it doesn't make any noise. I have to wait 1 hour or so, then it will start and I repeat the process over.

[libertyappl]

Most likely the cycling thermostat is out, you can test it with an ohm meter.

Here's the breakdown on your unit.
Model LE5700XSW0

Nat

[gman357]

What does this part look like?? My dryer gets louder when it's getting ready to cut off.

[denman]

My vote would be that your motor is just about shot. Probably a motor bearing. Also could be just a worn part overloading the motor.

The buzzing is it trying to start up eventually it trips it's internal protect then has to cool down before restart.

Check that the drum rotates fairly easily.
Do this when it is cold and again when it stops running.
Also a good cleaning of the interior and motor may help.
Check for any worn parts front glides, rollers etc.

Here is the link to your parts
Model LE5700XSW0

And a link with additional help
http://www.applianceaid.com/dryers.html