Check for a contaminated or warped flywheel.

Repair or replace the flywheel.

Check for a weak diaphragm spring.

Replace the necessary clutch components. Refer to Clutch Assembly Replacement : Diesel Engine  → 2.4 Engine .

Check for a oily contamination of the clutch disc.

Replace the necessary clutch components. Refer to Clutch Assembly Replacement : Diesel Engine  → 2.4 Engine .

Check for worn splines on the input shaft.

Replace the splines on the input shaft.