Well, there's a few tools out there for ya. One is the Outers foul out. Its ok. Second is Wipe Out. I really like it. You spray it in and let it sit overnight. Do this for two nights and it will get out the toughest stuff. Or get to work with your ammonia based copper cutter like you have been doing. For what you got, get some JB's. I like the polishing stuff. Not as abrasive. As solitary said, it will work wonders.