67 Dart windshield wipers not working

Thank you so much, this helped! I tested the motor,it’s good.The switch seems to have problems on the “a” terminal. I took it apart and carefully cleaned contacts and used dialectric grease, but didnt help. Seems to have power into switch from grey(?) wire but nothing else is hot. Maybe the switch is bad?
Check the connections in the bulkhead connector and make sure they are not corroded and are clean.