Robert, It Depends
I had the model that had the holding tank in the stern, under the 'swim step'. It was a monster to get out. The tank will not come out without cutting. Once you have made that determination, the best bet is to buy a small grider with a carbide disk. I used a roto-zip with an attachment. A saber saw will not work since the aluminum is too thin.As to repair, it is at best temporary. I used epoxy and glass fiber. Worked for one year. Did it again, same story. Then used an aluminum 'L' piece from home depot. Used Dow 5200 to adhere it to the tank. Worked great until another seam went out two years later. Then, the tank came out and two six gallon poly tanks went back in siamesed. Good luck, Rick D.