I dont think your supposed to get any grease inside the bearing. My throwout bearing just went out on me a few weeks ago. I pulled it all to replace it and it came apart as i was pulling the clutch fork through the bellhousing. It looks like something, most likely grease, had worked its way into the bearing area, been heated, and then got cooked completely solid, enclosing about 1/3 of the bearings and causing me one very bad day 100 miles from home. What a bitch to replace a $30 part.....