Hi Weston.

I hope this is what you are wanting:

Uninstall the 777.
Remove all of the CS_B777-XXX folders from FSX\SimObjects\Airplanes folder (back up anything in them that you want to keep) if any remain.
Check that the FSX\Captain_Sim\777 folder is gone. Delete it if it's there (again back anything in there that you might want to keep).
Run REGEDIT and delete the x770 and x772 entries found in HKEY_LOCAL_MACHINE\SOFTWARE\CaptainSim\ (32bit), or HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\CaptainSim\ (64bit).
Reboot your computer.
Reinstall the 777-200 Base Pack v1.2 - You will need to reactivate it!
Reboot your computer.
Reinstall the -300 and/or the Freighter if you have any of them (no need to reboot after installing these).