I have an Easicut 6000 XT which jammed. I loosened (do not remove) the bolts along the blade and gently prised the blades open a few millimeters. I them applied engine oil along the blade edges that rub together. I then re-tightened the bolts and all worked perfectly again. To avoid happening again oil blades regularly.
RogerH
May 2012
Periodically the trimmer blades should be oiled, as they will build up with sap & debris and bind them up - Weed-Eater trimmer user manual has a section on this.
If that does not free the blades, you may have to open the blade drive cam housing and grease the mechanism to free it up.