I have discovered yet another error in the schematic. The crystal oscillator input to the 1 Hertz clock must be bounceless and noise free. The circuit amounts to an RC circuit consisting of a couple of resistors, a couple of tiny capacitors and the crystal itself. I have found the required circuit in a book written in the 1980s. I'll change the schematic as soon as I can and show you the correct circuit. I can't believe there is this much work in such a simple clock, but there is.