I vote for two part epoxy. tape the out side with tape and gently slice along the tape crack . this way you only have to sand the inside . It leaves the outside w/o drip marks. At least thats what I do cause I have had the same problem. Roughing up the crack gently gives you smell feedback and creates more surface area to apply epoxy. oh and i use toolpicks as applicators. Wont tell you about the time i forgot to put down a paperplate underneath and was doing this on the kitchen counter.OUCh got in big trouble that time.