There is an Allen Head bolt in the center of the bottom of the head. The Allen Head recess may be worn down or full of dirt causing you to be able to undo it. If your Allen Head recess is like mine, you may have to drill it out. After removing the Allen Head bolt there is a release on the side of the +-4” plastic shaft cover. Push it in and the head will come off.
The big question is where to get a new trimmer head cheaper than from Sears? If you have a source please send it to me.
landmanathens, April 2008