The date wheels are incorectly indexed, I had a similar problem on a blackbird and it took me about 2 hours to work the maths out to get them correct again
basicaly on the date wheel you have on the left one 0011223 and on the right you have 0123456789 when the date changes from 4th to the 5th the left date wheel should change from the first to the second 0 but it is increctly fitted and is changing from the second 0 to the 1.
PM me if you want me to have a look at it for you