I went through this issue a few years ago. I tried flitz, meguiars polish, woody wax, never dull, scotch brite pads and a stainless pot scrubber. None of those products worked so I tried using different grades of aluminum oxide sandpaper, 600 grit and higher. It took the pitting out, however it will also remove the anodized or brushed finish which I thought looked worse. My hardtop frame only has the pitting around the top where the curtain slides in the tracks. I guess the previous owner left the curtains on and they held moisture against the aluminum which caused the corrosion. I just maintain it and try to prevent it from getting any worse. Let us know how you make out.
Pat