tools required:
craft knife
glue
clamp
clamp protection
sand paper
cloth
firstly place the chair on a table so the damaged area is accessible.
then remove all previous glue from the joint, using sand paper and the craft knife be careful not to cut the wood
once you have done that you can apply glue to the joint, all around the dowel and inside the hole
then slip them together make sure they are all the way inside the joint you may need to tap it together with your hand.
once the joint is together you can remove the excess glue with a cloth.
then place your clamp over the joint with the protectors on the wood of the chair and clamp up.
now leave the chair for several hours for the glue to set.
Job Done. 
