Only you know how adept you will be at assembling a glass aquarium. If you are good at it, it could be worthwhile to reseal (actually, disassemble and reglue) that tank. And, that is if you can afford or want to afford the time required. Otherwise, you can end up when you get through with tank that still leaks, with cut fingers, with broken glass, with silicone smeared on the glass, and with to little confidence to trust the tank in your house.
Used tanks usually sell pretty cheaply, so I agree with those who suggest just buying another one. Hexagon tanks aren't worth the effort, in my opinion, so if you aren't real enthusiastic about the shape, you could wait for a Petco sale and buy a brand new tank for $1 per gallon.