My delay wipers no longer work. I still have the reg and fast speeds.

When I put the switch on the delay position, the wipers wipe the windshield once, then a short buzz comes from in the column (I think) and then nothing. It doesn't matter where I have the delay speed position set. Once in a while when I put the switch on delay, the wipers will go very slowly and buzz the whole time.

I'm wondering if a good cleaning of the switch inside the column will fix this? Has anyone had this problem and solved it? Any thoughts are appreciated.

Cheers.