Scratch remover/repair for automotive paint. It comes in a squeeze bottle, and resembles automotive wax. You will be amazed!!! Be careful not to get it on the lacquer, as I wouldn't trust it on the finish..., and only use this while giving the complete horn a cleaning....,to give it a good rinsing off.
The tarnish on the slides rubs right off.., almost effortlessly!! I used it on the valves, too.,,, and voila!!
BE CAREFUL TO KEEP IT OFF THE LACQUER!!! ....,,,and you will be AMAZED!!!