The Timekeepers of the Millennium (1999)

In the center of the Earth is the Great Clock powered by 12 crystals. The Great Clock generates time for all the world. But one day in the year 1999, two crazy workers Cogs and Sprinx in charge of guarding the Great Clock accidentally hit a button that must never be pressed - which opens a time portal sucking all the crystals into it and sending them to different times in Earth's past. Cogs and Sprinx must travel back in time and retrieve the crystals to reactivate the Great Clock before the end of the year 1999 - or there will be no millennium.