If it were me, I would strip the lacquer off the horn. I love a good "raw brass" Bach. But, I understand, that does not solve the issue. So, again, if it were me, I would kindly ask the tech to refund the money I spent, and then I would strip the lacquer.
I have a "raw brass" horn (the Olds Super Recording I posted on another thread). Gotta admit, it is one of my best looking horns thanks to Maas brass products!