Veritas Chair Doctor Glue
Veritas Chair Doctor glue can penetrate narrow cracks in chairs. I used this on my kitchen chairs which had become decidely wobbly and they are able to withstand my sons rough treatment again - excellent.
If a chair has a loose rung, an injection of Chair Doctor Glue will first swell the rung & then bond it.
The low viscosity lets it soak into the end grain of wood, swell it and then freeze...