Check the pressure plate for out-of-true
WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Wipe the pressure plate friction area clean.
Check any out-of-true carefully. Use a ruler and a feeler gauge. Out-of-true is permitted in one direction only.
Out-of-true must not exceed 0.2 mm . If out-of-true is greater, replace the clutch.
The clutch must be replaced as a complete unit.