We had a customer who bought our clutch. After installing the clutch, the PIS setting was set and the clutch was running smoothly. Our customer wrote to us that on the first PIS setting, they got the clutch to run very smoothly. After 300 miles, it started bucking and not running right.
We have never experienced an issue like this. We were complexed and flustered why this is happening. The clutch was getting worse so the customer decided to take the clutch out. After looking at the pictures, we see line of something like grease or oil or fluid coming from center of the flywheel.
Looking at the flywheel, we notice that there is a leak that's coming from possibly the pilot bearing or rear main seal. It is also possible that too much grease was applied. Please take a look at the pictures. Look at the red marking. Please excuse my not so great graphics. As you can see, the grease got on the friction part of the flywheel and consequently that grease got on the clutch disc and cause the clutch to slip. The leaked grease damaged the clutch unfortunately.
That's why we always recommend replacing the rear main seal and pilot bearing and the throw out bearing.