Our team really had troubles with the indexing of the frisbees and how or if to even flip the discs. We decided in the end that instead of trying to deal with flipping them to just reject them totally, and move on to another disc since we believed that there would be plenty of other discs on the floor.
Here is the footage of us picking up the discs right side up and then again at 1:30 rejecting the upside down discs. We did this by the slot between the 2 levels of the elevator and using the top curve of the disc as a guide of sorts to filter the discs up or out of the elevator.