Is it plane specific? Or is it happening in all bombers?
Take off, level, go to bombsite, hit U, hold Y for a count of 5, let go, hit U again.
If it's still red, try the following
Take off, level, go to bombsite, hit U, do the whole bombsite mark-the-spot thing, holding Y for at least 5 seconds.
This isn't going to hit anything accurately, this is just seeing if you can calibrate at all.
Is the text still red in both cases? Does it show any speed at all (defaults to zero?)