John, Here are some pictures of the inside of the pendulum's cast brass shell and the discs that were inside of it. The bottom two discs are steel (one is used as the bottom cover), the next two discs are brass, and the last disc is copper. Note that the inside surface of the cast brass shell is inscribed with the movement serial number. Also, the two brass discs are stamped with the numbers 2055 and 1248. A number.40 suspension spring was put in the clock yesterday afternoon and it ran approx. 16 hours, gaining only 5 minutes, before being stopped to inspect the inside of the pendulum this morning. So it seems like it will be easy enough to get it regulated now. Thanks again for the information that you and Eric have provided. Pat L.