I've built 2 clocks, a grandmother clock and grandfather clock. The difference is size. The grandmother clock had run for 40 some years and the mechanism was worn, so I replaced it. It is doing fine. The grandfather is another story. It ran fine for 8 years, I oiled it every 2 to 3 years. The last time I did, it had quit chiming. Oiling did not fix the problem. I got a professional and he redid all that i did. It ran great.............for 15 minutes after he left. He came back 4 times and could not get it running longer than 12 hours. He quit and refunded our money. He gave up. A good clock guy would NOT give up. Anyway, I got a bright light and some magnifier lens and watched everything operate......many times. I did find one thing, the hands were on so tight that I had to use pliers to loosen. After that, it has run 24 hours and doing good.
Do you think that the hands being too tight could have caused this? I checked the web and got varied answers. If it keeps running........I'll have to believe that the tightness was the problem.