i recently had my echo trimmer head stop rotaing. the engine is perfect, but the head just doesn't turn. iwas told from the "dealer" that its probably the clutch, and its going to cost about $160. i just poolked for the first time and realized the clutch for my trimmer is $35. its only a 2100, but its still really strong. how big of a job is it to replace the clutch, never did it?