Use this and it will clean out the blueing
It's called blue job. It's on eBay
Had much success with it before
It works, blue away or blue job, or whatever they call it, don't need much and have used 0000 steel wool as well. it helps, but for me anyways, the blueing/copper color is coming back again after a few years. Doesn't really bother me as when I first bought it, have learned to live with it.
After all, it is a 15 year old cycle.