Almost certainly, the diecast lever behind the rotary dial will be broken. It converts the rotary action into a push and pull motion. Unfortunately, VW saw fit to route the cable in a deep U shaped path through the firewall to the tap under the expansion bottle in the engine bay.

I tried to fix it back in the day to no effect and resorted to a generic choke control switch mounted on the empty panel below the heater controls. It's worked perfectly across the nearly two decades since.