1. Grind centering holes in the corroded rivets with the #945 grinding stone. Next, drill out the rivets with the #150 drill.
2. After removing the old corner, clear away the old sealant with the #121 high-speed cutter.
3. Position the new corner and drill holes for the pop blind rivets. When drilling, try to use the same holes from the old gutter corner.
4. Use a pop blind rivet tool to install new, color-matching rivets. Then apply a sealant to the joints (sparingly) so water doesn't become trapped.