Hi , got an electric Ryobi (corded not battery) RLT1238, appears the line spooler is spinning (high rpm) but not cutting any grass, and when undoing the knob at end of shaft (looking up, bottom of unit rotate anti clockwise) think it lwould normaly lock so you can undo the round knob to take the line spool off, but now appears to spin freely in anti clockwise directions so you cant undo it. Sometimes the bolt in plastic knob casing gets hot and melts or wears out the plastic hexagonal recess in the knob and spins freely but i replaced the spooler and knob so its not that. Suspect its geared so it might have broken or burnt out at the electric motor end or shaft has snapped. Anyone know what meaning and come accross this issue? sounds counter intuitive to throw the thing in rubbish and spend another $200-330 for new line trimmer, when it might be able to repair it myself(no its not under warranty). Im thinking the shaft hasn't broken but some kind of gear locking mechanism has broken? parts diagram? exploded view? anyone?