Intermittent wipers too intermittent, 97 Intrepid

My 97 Intrepid' intermittent wipers usually work ok, but periodically they
will stop functioning in intermittent mode and low speed. When they do
quit, the wipers just stop where ever they were (not just the bottom stop
position). When this happens, I have to switch them to high speed (will
always works). I am guessing either the motor or the switch, and was
wondering if anyone else had the same problem and could steer me in the
right direction / solution.

Thanks,
Mark