My wild guess is, the craft was loaded with junk to be recycled, melted down, reused, etc, and by that time the mechanism was no longer keeping time, with the inventor long gone and unable to refabricate it or make the adjustments. They had no mass production for stuff like this.
Kings and emperors always wanted to know the future, so they had court astrologers. Maybe it was a government project. Sorta like the Manhattan Project of its time...................