I have the same need. Several years ago I sent my motor to a place called “Vintage Wipers” (or something like that). I called the owner and he sounded good. Several weeks later he sent it back and told me he didn’t want to work on it. So much for that.
I found a place called D&M Restoration (https://dandmrestoration.com/wiper-motor-restoration/) that appears on the surface to be a pretty good prospect. I haven’t contacted them yet but they look hopeful. If you use them please report. I’ll contact them when I get back from travel in a couple of weeks to see if they can handle mine.
If a person has already made an ID on the wiper unit as being one of the three manufacturer's models then at least you know it's for a model A. Some rebuilders won't repair or restore the newer models such as the EA Labs units and other aftermarket products that were made long after the model A production. Of the manufacturers Owens-Dyneto, Heinze, and EA Labs, some were better than others. Only a few reproduction parts are available for some of them. The little motors may or may not be rebuildable but I still find used units that function. They need service and a lot of TLC to get them back to functional condition. I imagine rewinding the little armatures may be a difficult task if they are damaged. The ones with zinc die cast parts like to break and repairing them in not something I would want to do. Condition is everything. The guys that do the horns may take them on but I don't know for sure.
Steve Smith might still do the armatures. Steve Smith, P.O. Box 505 , Morristown, IN 46161. Email: taillight@hrtc.net (from MARC Technical) I don't know if he does full resto or not.