[Radioroslyn]

Here's a few pic's of one from a 16 code 121. It works like a small transmission where you pull out the tuning shaft and it moves the one of the rubber wheels. This changes the ratio that the tuning cap is turned by shifting the rubber wheel and it's contact point to a larger or smaller wheel. The small looking "gear" below the tuning shaft comes in contact with the rubber ring that is fitted around the outside of the dial thus driving the tuning cap. At the back end of the tuning shaft there is slot around it. That's where the spring snaps into, it gives it a positive feel when shifting.