Hi, I was asked to look at an old mantle clock with a basic English made pendulum movement. The suspension spring for the pendelum was partly missing with only the top part left pinned. Is there anyway of calculating the size of a replacement spring? I can work out the possible mid-position for the pendulum and lever rod assembly but do not know what strength (ie thickness, width, length, number of leaves etc) the spring should be. I have returned the clock now but wouldn't mind having another look at it if I can solve the spring issue. Can anybody give some guidance. Thanks