I was impressed with how well this formula works on removing tarnish from brass terminals. The terminals on my nos 42wla keyed ignition switch were tarnished dark black. Not just the external wire screw terminals but also the ignition contact terminals inside the switch. Not liking the external wire screw terminals to be tarnished and fearing poor conduction, I decided to disassemble the entire switch. I am glad I did disassemble it. The internal contact terminals were just as tarnished. Mw wife provided me with the following solution from her home made cleanser recipes.
You need 1/2 cup white vinegar
1/2 teaspoon salt
Mix the salt with the vinegar
Mix flour into the vinegar and salt solution and continue to add flour until mix becomes pasty.
Apply paste to brass terminals. Cover with paste well.
Let stand for 10 minutes
rinse of paste thoroughly
Dry with cloth