Back up language.dll first from both Prepar3D and FSX.
Copy and replace language.dll from FSX to Prepar3D.
(use the backup file to undo that and everything is back to normal)
Now Prepar3D can start with trackir 5 working fine but the engine on any given aircraft will not start. Some of the menu items are amiss. Looking at the dll files for both they are close but not the same. I have a hunch that a modification to the language.dll file may be all that is needed to re-enable native trackir support for Prepar3D. I am aware of Ezdok so I'd rather not hear about it in this thread. I'm wondering if anyone is able to make the modifications to the language.dll file to get trackir working again. Prepar3D moderators claim it is a window menu item. LM and NP are blaming each other but I have a hunch it really is as simple as a modification to a dll. I am not savvy with dll modifications it is out of my scope. Trackir support in Prepar3D is enough for many to abandoned it or continue using it.