Helo Michael, your post pushed me to solve my own problem.
I have the samed problem on my NC33 mkII 1978, the center wiper no longer runs but smells like a major fire when actuated.
A camera picture shows “TYPE WWF, 12V, made in USA” engraved on the motor case and RWS on an aluminium leg on the right side.
A googol search shows it as “American Bosch WWF Windshield wiper”, probably used on many WW2 jeep, looks very common on the other side of the pond.
An article http://www.earlycj5.com/xf_cj5/index.php?threads/rebuilding-american-bosch-wwf-electric-wiper-motors.124208/ explains how to rebuild it, very interesting even if plan to exchange and not rebuild
Many motors are available on the net, one has to specify shaft length thus one has remove the windshield and take measurement.
What other specifications and measurements are needed to replace the motor or the entire wiper, I do not know yet.