The lighter piece I am referring to is the plastic washer on top of the plastic gear. I originally thought it was broken off of the gear but it is clearly not part of the gear. Yes there is a metal gear below the plastic one.
therotisserie still works but last time I used it, second time ever, I had a turkey on it and it would spin a little then seem to get hung up and not turn. Weber said it should be able to handle a bird up to 20 lbs.
I'm pretty sure this is what I dealt with. After the collar/shank separated from the main gear it would ride up and lose contact with its mate, and the output shaft would stop turning. I repositioned the gears so they'd work, added the clip to keep the white gear and its broken part in place, greased the jiminy christmas out of the works and put it all back together. I use my rotiss only a couple of times a year and so far so good, but I expect to have to eventually replace the motor.