Intermittent wipers not working

I have a W211 E320 and have a problem whereby the wipers wont work at all on any setting nor if I push the stalk in to the wash position. Have noticed that if I apply slight pressure on the wiper arm in an upward direction they will then work however not in the rain sense position. I am inclined to blame the rain sensor however didn't think it would cause the wipers to stop completely. Any advice would be appreciated.



