Not sure what year you have, but I found on my '67 that when the wiper motor is parked - you can attach the wiper transmission in two positions. Sort of like a distributor.

I would try disconnecting the wiper tranny from the motor, rotate the wipers through 180 degrees and reattach.

And I found that taping popsicle sticks or toothpicks to the ends of the knobs where the wipers attach to observe wiper motion sure helps to prevent wiper arms from tearing into the cowl panel area.