My whirlpool duet sport gas dryer model # WGD8300SW1 works fine but suddenly started making a loud screeching or scraping noise after it has been running for about 5 minutes. It ran a full cycle of 40 minutes with no sound when I had the gas off but when I turned the gas on and started the dryer, it ran about 5 to 8 minutes then started the scraping screeching noise. I tried to pinpoint where but was unsuccessful. Is this something I can fix or should I call a repair man?

You will need to tear it down. Read these: https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20Dryers.zip
What you need to do is to remove the dryer and take it apart. When you pull it out from the wall and unplug it you will be able to see what you need to do in order to take it apart. It is not that hard to do. Have dryer on its back to make it easier to get the drum out. The first thing you want to do is to clean out everything very well which means to remove parts that move air and wash them out with soap and water, including the door and blower fan. Just vacuum out motor. You always grease bearings in a dryer with white lithium grease, available at any appliance or auto parts store, but yours are probably too scored to save by now. Replace them. You also want to get a belt for the dryer unless you want to do this again in a month or two. It is only about $5.00. Put it all back together and test the drum by rotating by hand to make sure you have it right because many errors can be made in putting it back together. If you have labeled all wires when you took it apart you will have no problems. See: https://dl.dropbox.com/u/8010163/Kenmore%20Dryer%20Manuals.zip
https://dl.dropbox.com/u/8010163/Whirlpool%20Dryers.zip