Here’s a video showing how to repair both blend doors using plastic plugs from seller DSP on eBay. It turns out many VWs from the same era have the same problem. When researching that VW problem, I noticed that the blend doors are almost identical, and the plastic plugs work actoss both.
This method goes through the center dash vent behind the radio, similar to other repair methods.
https://youtu.be/ZiFFllCzlxc