Had a small issue with the number pad last month with a unit I bought @10 months ago; the 2-5-8 line would enter 3-6-9 respectively. The 1-4-7 and 3-6-9 numbers were okay. Russell's were great and made an exchange on the spot.
I had the exact same problem the second time I used it - very common so I hear. I was all ready to send it back, and it corrected itself. Left it unplugged for a week or so and when I tried it again, it was ok. Fine every since, but I'm waiting...........
Quality Control on these seems to be poor.