[thabaer]

Pull up your driver side carpet and floorboard. Check the hole where the cable pin fits in the clutch pedal arm for deformation. If you've gone long enough with the tranny-mounted helper spring broken or missing (heavy feeling clutch), that hole will be oval instead of circular.

Another possibility, though rare at this point in time, is that you still have a rubber-center clutch and pieces of failing rubber are getting into the engagement surfaces.