I finally got down to where I can see the motor. The large cast arm going to the back of the motor is broken at that point. If I loosen the bolt on the opposite sede of the winshield wiper assembly and loosen the bolt on the white plastic thing-will the whole thing come out?

Where does the wiring come loose(hopefully unplug)?

Also, can that cast arm be bought as a seperate item or do I need to buy a complete windshield wiper assembly?

Any secrets I need to know to tackle this repair?

 

You can buy some parts seperate but it depends on your car. Usually the plug is easily seen or it goes into the fuse box and then unplugs.