Hi john
i have one of those spindle boards, as depronman said it's a good little board.

By spindle reversing relay i take it you mean Rl3 in your Boxford, if so the terminal numbers are printed/stamped into the relay holder ,just above the terminals so either use a mirror or take photos of the wiring and also take some more when you have removed the top set of wires.

Or if i remember tomorrow i can pop a pic of the base up