Firstly check the wiper nut. Its possible that the grip has worn on the wiper arm. Check this by trying to move the wiper by hand. Look for obvious movement at the nut.
Secondly, if the above was not successful, get under the bonnet and remove the plastic covers around the wiper motors. It should then become obvious if one of the linkages has dropped off.
Rich.
Was quite a funny site the pair of us turning up at the services with a passenger wiper working only. Both bust en route.
You prob replaced the motor as the scrappers wouldnt sell the linkage seperately. Mine swore blind they would not seperate. But I managed it and took them back the broken motor they sold me