Hi mate, this happens for several things, the hub is no longer working properly if you add that the dust from the disc wear makes the shaft of the embankment hard even harder to discard the hydraulic system try the following remove the slave cylinder from its housing without disconnecting the pipe (the one from the gearbox) very important for someone to hold that does not get fired when expanding by stepping once the pedal is released up and confirms that you can return the cylinder by hand if that is how the hydraulic system is perfect Next to check is if the shaft of the embrage hole is seized or finally what they tell you about substitution joint embrage check what I say and comment what you see a greeting