The blend door control arm was not connected and the control arm was frozen in place. When I placed the control cable on the arm, the pot metal arm disintegrated. Has anyone had an issue with this control arm when replacing the blend door or removing the blend door?

The blend door control arm appears to pressed on the the door shaft. It is not clear how the door could be removed if the door and the control arm are permanently attached.

1987 Firebird GTA.