Clock Repair / Questions

I have this clock, I don't really know much about it. I remember the bottom ball like things use to move around / spin. They don't do this anymore. They haven't done this for a long time. It still tells time just fine. I'm wondering if there is any information someone might have on this clock and either how to fix it or to tell if it would be pricey to get it repaired. It says Howard X Miller on it