Remove the ring, carefully remove all the old glue, roughen the inside surfaces of the ring & re-glue using non-waterproof wood glue. This might seem strange but the theory is that the wood glue will not form too strong a bond so that if the ring gets knocked & cracked there is less likelyhood of the wood being damaged. Also if you need to remove a good bell ring at any time just soaking the end in water will soften the glue. (Think I got this from a well known bassoon maker & repairer)
