I have a Burke high D whistle (brass) and a Chieftain low D (alloy). I have had both for many years, and have never done anything to them to keep them in decent shape, except for the occasional buffing of the exterior. Yes, I’m ashamed of myself. So what should I be doing, and how often? They both sound fine to me, but maybe it’s because I’ve gotten used to less- than- optimum sound quality. Thanks for your help. And go easy on me.