Pull the dust cover from the bottom of the bellhousing, have somebody depress the clutch pedal then check the clearance between the disc and the flywheel or pressure plate. If there is clearance, see if the disc will move forward and back on the input shaft splines.

If it won't move for/aft the disc is too tight on the input shaft, if it will move for/aft but won't spin the pilot bearing is too tight.