In the center of the head Anthony there should be a plastic knob? This knob actuall houses an INDENTED HEX head bolt that screws into the end of your trimmer shaft? NOT knowing your make of trimmer however, not sure if it is left or right hand thread? Most are normal right hand thread so turn counter clockwise to remove? IF not, then turn clockwise to remove? This should get your spool out where you can restring it? Hope this helps...
R Stuart, July 2008