if it is a glass on glass connection than it can just be re-silly coned. you will want to clean both surfaces very well. it might be easier to remove the brace entirely to make sure it is entirely clean. using a brace to keep the tank from bowing is a good thing while you do this. once it is clean, just run a bead of silly cone on the ends of the brace and place it back where it was. clamp it firmly there for at least 24 hours. 3 days would be better. remove the brace slowly to make sure it held and you should be good to go. you can leave the brace there at a slightly loosen possition as a just in case for the next week to be safe if it makes you feel more comfortable. this is how tanks are build.
G~