Back in 1994 I made a photographic study of Flanger OK at Chama. The photo below shows the important detail of how the target shaft is rotated. The shaft has a collar at the lower end with a groove that spirals down the collar. The bracket coming off the flanger blade lifter assembly has a bolt that rides in the groove. This spins the target shaft as the blade is raised or lowered. The target shaft is mounted with pillow blocks to the target brace to allow it to spin. Hopefully that all makes sense and the photo provides enough detail.
Dave