The anniversary clock or 400 day clock is one that has been around for a long time. To this date there is a lot of repair shops that won't repair the 400-day clock. Needless to say it has its quarks. Believe it or not that to repair one you have to have the book. The suspension spring that the pendulum hangs on has to be the proper length within .050 of an inch and the right thickness. If its not it won't run right. I guess some people think they are above a repair book. But without it you'll be lost. Anniversary clocks aren't hard at all to repair. The cleaning of one is different them most other movements. The best way to clean one is to dismantle the movement and clean all of it with mid soap and water. The reason being is that the brass plates of the clock are polished and then covered with a clear coat that prevents them from tarnishing. The strong cleaning solutions that work on all the other movements will cut this clear coat and then you will have a clock that is under glass and ugly. What's the point of having a clock for all to see that you want no one to see? The biggest problem that people run into is that it's a bear to put in beat. That again takes a special tool. I guess what it comes down to is making money. Sure it takes longer to repair a 400-day clock for some people, but for the most part a good clock shop should be able to repair it for around 70 dollars. With the right tools and experience it's no harder then an early American mantel clock. Everyone in the clock repair business has to be in it for the money, that's what running your own business is all about. If you have a hard time with a certain type of clock sure stay away from it if you're not going to make any money on it. But how can you be called a clock repair shop if you only take the ones that are easy to fix. Do you want to eat at a restaurant that only serves scrambled eggs because they don't know how to make an omelet? Just remember that it's your clock and just like anything else that you take to get repaired you have the right to know what they are going to do to it. Back to the clock. The pendulum on most all other clocks swings back and forth. The pendulum on a 400-day clock rotates back and forth. It should rotate at least 270 degrees. If not it is loosing power some place. The escape wheel is what puts power into the escapement in turn giving the pendulum a little impulse to start rotating it in the opposite direction. On the bright side, if you wind your anniversary clock in 1999 the year 2000 bug won't make it crash.