shifting is getting tough in my 85 528e manual tranny car. it feels as if the clutch isn't fully disengaging, making it tough to stop at traffic lights and shift into first gear. Tonite driving home I resorted to RPM matching to shift gears rather than using the clutch so I wouldn't grind gears. Is this a sign that my slave cylinder is going(gone) bad? Where's a good place to get a new one?