Does it seem like it is catching on the top?
There are two hidden screws. If you have no side panels on the unit pulling the unit out about two inches will give you access to them. If you have side panels the panels will have to be removed as well as some trim peices to get to them. Below is a blow up and a service manual.
Service manual click here
Sears link photos
On the sears link click on the photo and open it in a new window to blow up the photos.