M-B C240 4matic Winshield Wiper Controls
 

My 2004 M-B C240 4matic has an issue with the windshield wiper control. It only works when you push in the the left control arm to get a single wipe. If you twist the control for intermittent or full time wiping, it does not work.
Since the wiper works for a single wipe, I assume the problem is not mechanical but an electronic control issue or maybe the switch itself.

I would appreciate any suggestions on the diagnosis and repair of this problem. The only thought I had is that the voltage of the old battery may be low which may affect the electronics. But this would affect other controls. Thank you.