I have some 400-day clocks that work, but then after a period of time (days to months) - especially if I move the hands to correct the time, the clock stops and will not go. Most times I remove the hands and the clock runs. Hands back on - it stops. So, I am thinking that the problem is that little cupped washer behind the dial on the main arbor. Am I right? If so, does it mean that it lost the curve of its cup, and thus it needs to be bent slightly to increase the curve? Just trying to figure it out to get several of my clocks running again!