rudder trim in fs2004 won't hold heading. how do i fix it?
I think we might need more information here:
What controller are you using (joystick/throttle set, make and model etc)?
Aside from checkng dedicated FS2004 or flight sim boards for tips, the most obvious things to check are updated drivers for the controller, and ensure it is the only control type selected for the rudder (e.g. if the rudder is also set to respond to mouse, that could cause issues).
You've made two threads about the same issue, which is usually frowned upon, by the way.