The destinations need to be programmed with this change facility ie "Slievemore D10" changing to "Shantallow D10" if the blind can do that. The Ultras have the old generation flip dots and so don't have this facility.2838 has the LY destinations, and maybe because they came from LB the programmer was told to put the country destinations on them as well so that they could be used on the country. Don't forget, destinations on a fleet of flip-dot displays can be changed in a few hours. Maybe the
I think 2756 has only the Destination "D10 Slievemore" not the usual Slievemore/Shantallow
2758 has the Ballymagroarty destination stuck on it and can be found on the early Curryneirn runs until 14.30
2759 destination works the only other one that doesn't work is 2755 which is set to blank which can be found on the early Sleivemore runs at 08.18, and every 40min until 13.40 (at least).
You also say that either 2841 or 2845 have a broken destinations, the buses can be set so that there is no destination by typing A000 (then press enter). or do you mean that some of the dots stick, if so it is 2841 that has one do that sticks on yellow, but soon falls back to reviel black. Most noticable on the destination Altnagelvin via Irish street.
HTH
Ciaran