I have been in the process of restoring what I believe to be a Horace Tifft banjo clock. All I had was a damaged case so I had to buy a movement, weight and pendulum. the movement is a fairly early banjo movement. I purchased a 7 lb weight. The clock runs slow no matter how far up I put the bob. I tried a 6 lb weight but it got slower. Any thoughts as to the correct weight or other reasons the clock runs slow. If I shorten the pendulum it would be up in the throat of the clock. I do at least one restoration a year. This case was just such an interesting case I wanted to try to bring it back as best as possible.