Biohazard

The straight razor method does take some amount of practice to master. I nicked and gouged paint a plenty learning it. Then we switched to that big erasor wheel. No more nics or gouges. You do need to keep the wheel moving or you will burn through the paint eventually. And seeing how your subtrate is aluminum,which would probably nick easily,the wheel is your best choice. I see you already did some grinding to remove the tape. I hope the metal is still good? Too course of a grinder and it can remove a lot of aluminum in a hurry!