I use a fluid epoxy called GIT-ROT sold in boating stores to repair dry rotted wood and give it strength. It would probably be good to srenghten checkering also though I have not tried it for that purpose. It is made by BoatLIFE div. of Life Industries Corporation PO Box 71789 Chareston,SC 29415-1789. All oil should be removed by a soaking in solvent. I flex the cracks open and pour in the epoxy. Clamp or use surgical tubing as sold by Brownells. Soaks in to the crack and is strong.