I believe some factory foremen's production records used to pay pieceworkers are available, but don't quote my sometimes (OK, often) faulty memory on that...How were the “completion” dates discovered. It was my understanding that these date are not available,
They do show up on ebay from time to time since they were standard for five years from 1905 to 1910. Pristine pair will cost over $200, while worn sets might be found for $125. Curtis Harlow will bring any set back to life if needed. They are worth restoring since these were made with Circassian Walnut.