My Mac Pro 610 clutch slips so bad it won't cut anything. The last time I used it, it was OK, kind of odd now all of a sudden it does't work. The bar is pretty wore, probably needs replacing, but I don't think that would cause it ti slip that bad. Seems to be worse when used sideways, when cutting a tree down, but still not good when "upright". Does a clutch go bad that fast?