Take it apart and relieve the tang area on the inside so the action isn't acting line a wedge to split it. Don't get crazy and make a gap that will show from the outside,just make sure the action isn't what is splitting it. Put some accraglass, not the jel, in 2 jars like baby food jars and heat it in some boiling water until it is really thin. Use the heated epoxy to fill the crack. If the crack goes all the way through so you can get at it from the inside you can take a razor blade and cut the inside a bit wider to hold more epoxy.

Don't put any oil on it at all! In fact clean the area several times with acetone from the inside before you glue it.

Pour the epoxy on the crack from the inside but you will have to tape the outside and build a dam on the inside to keep the epoxy where you want it. The tape over the crack on the outside keeps any that gets through the crack from running onto the stock. The little dam inside keeps it on the crack and off everything else. When you get done clean up the inside with a dremmel.

When you are mixing the epoxy get both parts hot before mixing together. It will start to set up fairly fast after you mix them together.