Opinions on re-sealing.

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Just picked up a used 50gallon 36X18X18 9mm glass aquarium to replace my 40 gallon breeder (wanted the extra 4 inches height). The silicone seal on one of the corners is a little worse for wear and worn thin in a section about 3 inches long. Is it recommended to redo the entire seal? Can I leave the panes siliconed together and just cut out the entire corner (and bottom) seal and redo? Or do I have to pull all the panes apart and rebuild the entire aquarium? Below is a pic of just what I am talking about.

Thanks in advance for any advice!