W220 wipers intermittant

[dhs9]

On my 2000 S500 I turn the lever and sometimes the wipers start other times they dont. More often than not they dont. I checked fuses/relays and cleaned still not working. The switch is good because whenever the wipers quit I can hear a slight click when I turn the key on and feel a nudge in hte wiper blades. Do I need to lube or change the wiper motor? Thanks for the help