Road test the car and listen for a metal clicking sound from the front when driving in slow circles on full-lock by a full left and full right lock to check. This noise may also be apparent when pulling away from a standstill with the lock on. A clicking sound is indicative of wear in the outer constant velocity joints. If vibration, which is consistent with road speed, is felt through the car on acceleration, there may be wear in the inner constant velocity joints. Constant velocity joints can be dismantled and checked for wear and if found to have wear, the joints should be renewed. Currently it is unknown whether the driveshaft joints are available separately, or if it is necessary to obtain a complete driveshaft, and therefore it is advisable to consult a Volvo dealer or parts business for further information.