I can only recount my personal experience with Ficken (Wiperman.com). I did all the recommended tricks to get my '49 Packard wiper motor running but nothing worked (I could get it running while disconnected from the cable mechanism, but it didn't have enough power to run the wiper blades). I ended up sending it to Ficken and got it back very quickly. The cost was reasonable. The wiper motor runs like new. I would have no problem using them again.
Edit: This was some time ago... July, 2009. However, the wipers are still wiping.