Ah, it seemed like it would be either related to the diameter of the guide rods or, lesser so, the height of the base for keeping the rod level (if the trammel point can't be height adjusted).
You could make a trammel point for you 1400 guide rods: block of wood the thickness of the base more or less, a pair of
loop clamps on the board to hold the rod, a pointy screw driven through the block as a trammel point.
