Our 140yr old Italianate house has beautiful wooden quoins forming the
corners of the house. Each side of the corner looks like a series of
blocks with raised panel centers.

Unfortunately, many of the quoins now have horizontal cracks in the
wood up to 1/8" or so wide. I would like to repair rather than replace
them since matching the detail and quality of wood would be very
expensive.

I could obviously just have a field day with caulk, but I was
wondering whether there was a better way of restoring the wood. I
considered using a wood epoxy but wondered whether the gaps are too
narrow and how it will behave under seasonal contraction/expansion.

So any suggestions on how to patch up these cracks?

Thanks!!!