1995 Nissan Other

This should be trivial but I'm new to Nissan. The wiper motor assembly is apparently secured to the wiper linkage by a " stop ring", as the Haynes manaual calls it. This " stop ring" is translucent plactic and looks a lot like a small bowl in reverse. Can anyone please tell me the correct way to remove this " stop ring"? Or, is this plastic bit just a cover for the " stop ring"? It's hard to reach and thus hard to figure this out.
BTW: wiper symptoms are that the wipers are " dead". During troubleshooting I found that the motor runs when 12VDC is connected across the 2 dark colored (of the 3) motor wires, but not when one leg is applied to the red wire (of the 3).
I don't have a diagram of the internal motor wiring, but I suspect that the red leg is a tap on the windings (and may be open). Any input on this is welcome, as would be diagrams of the wiper motor and/or control circuit.
Thanks in advance
April 28, 2006.

Check out the related content below while we wait for the question to be answered by a professional mechanic.