Sounds to me like the throwout bearing is dry. Since the bearing is sealed,
I'd expect that a new one is in order. You may find that the clutch and
pressure plate are due for replacement. If so, don't forget to have the
flywheel resurfaced. The machine shop will usually be happy to replace the
pilot bearing if they have it in hand.

When things are going back together, a bit of high temperature grease should
be used --
four places on the clutch fork (Where the slave cylinter rod contacts, The
socket for the bell housing swivel ball, and the two fork ends.)
on the pilot bearing
on the tranny input shaft where the throwout bearing slides
on te surface of the throwout bearing that contacts the pressure plate
fingers.
on the surface of the throwout bearing sleeve that the clutch fork rubs
against.

The inside of the bell housng is usually quite cruddy, due to an oil film
and clutch residue. A good cleaning is appropriate. Check the front tranny
seal and the crank seal for leakage, and replace if necessary.
Care must be taken during tranny removal and reinstall. It's possible to
damage the pilot bearing, the front tranny shaft, and even the front tranny
bearing.

Others may disagree, but I'd also flush the tranny out by filling with a
mild to moderate solvent and draining several times, then replacing the
tranny lubricant. I'd change the lubricant again after no more that about
one thousand miles. You would be suprised to see how much metal powder is
present on the inside of a moderate milage tranny!