john, this is a direct drive model, so maybe the drive shaft has slipped out of the drive points at head or at bottom of shaft. try loosening the bolts at head and pushing shaft in thight, then tighten holding bolts. repeat operation for trimmer head end. also ensure that trimmer head is fully engaged onto shaft, sometimes they seem to be engaged but there is a.5cm shortfall.
otherwise, maybe the drive shaft iteself is "tired". easy to fix, as these are almost a universal product. any good mower shop should have replacement drive shafts
bill., October 2007
