
Have you contacted the NDTR about the illegible tattoos.
I had problems with one litter where they were done by a different person, and she no longer tattoos. My tattooist said it is vital that they are done correctly. the pups ear must be shaved even if it looks hairless (which is what didn't happen in the case of the litter I mentioned), and the ink must be massaged in sufficiently.
If you have tattoos that are poor they will re-do them free of charge (in the other ear) and cross reference the records.
All mine are done with black ink and all are very legible, (even to me with very poor eyesight), they are easiest to read if the ear is wiped with surgical spirit (or water).
I did find the two that were done with the old large callipers and green ink harder to read, but still decipherable, both these dogs are now dead. The oldest of mine done with the small callipers is 9 1/2.