Greg:
A couple of things I forgot to mention.
- Your bath temp may be too high. Temp range for the original formula is 60-90º. 60's a bit too cold, but 70-80 works good for me.
- Your wiper motor housing may be too big relative to the size of the anodes.
Commercial recommendations say no more than 1.5 to 1, part to anode size. I tried that once, a 36" part w/24" of anode. It did NOT work well. So I always make sure my anodes are at LEAST as much area as the parts I'm plating.
How big is that housing? Length x diameter. From the picture, I'm guessing about 4" x 4"? If that's close, then that part has near 63" of outer surface area! Even if only 3x3, thats still over 40".
How big are your anodes? Is the inside of the housing completely masked?
Sean