I would suggest you ask this question on an antique restoration forum.
But if it was mine, I would try to open the crack just enough to get some wood glue into it, then put straight pieces of scrap wood either side (to protect the original wood) and then put several clamps across the scrap pieces of wood. Be careful not to glue the scrap pieces of wood to the the original.
If you cannot get wood glue into the crack, you could use low viscosity super glue - this will seep into any cracks. You will have to clamp it quickly though if you use super glue.
If the screws not holding continues to be an issue, you could fill the holes with woodfiller and re-drill.
All,
I would appreciate your advice please.
The images in the link below show a crack/split in the chessboard I've owned for 35 years, but I only recently knew about after I started playing chess again with my daughter.
https://imgur.com/a/KpEwG2S
I should be grateful to hear what you would suggest is the best way to fix it please?
Some points to note:
Many thanks,
JC