HI, The only way to remove all the corrosion is to use acid, called in the paint world metal conditioner, there is one for steel and one for alum.
There should be a paint store in your area that sells auto paint, you will find meal cond. There and a lot of free advice.
I would not use just scotch bright all your going to do is damage the alclad the corrosion will come back. You will have to repeat the metal cond. Again before you paint,
I worked on a paint crew for several years painting new 747ís 727ís ect. We did not scotch a whole 747 new alum , old alum with corrison dif. Story acft washed with strong soap , metal cond, , was again , dry good, etch primer , primer for type on paint used, top coat, depending on order clear coat,
Long story short, you need to remove the corrosion shown in the pictures its only going to get worse, hope this helps you.