SF Man wrote:

Do you know what chemical can clean an anodized aluminum Mag-Lite
flashlight when Duracell March 2013 alkaline batteries leaked.

The flashlight itself seems to be black anodized aluminum. The bottom
Duracell March 2013 D-cell battery leaked and started corroding the steel
spring in the bottom end cap. It left a gunky grayish white gritty goop on
the spring.

Likewise, the grayish gritty goop expanded the battery such that it was
stuck inside the 3-D-cell flashlight. After about 10 minutes of banging
upside down, I was able to extricate the three D-Cell Duracell batteries.

I generally use vinnegar to clean up scale in brass water faucets. Do you
know what chemical I can use on aluminum & steel flashlights to dissolve
the grayish gritty goop from a leaked alkaline battery?

What is that goop made up of anyway?

You don't clean it, you call the 800 number on the Duracell batteries
and then follow their instructions to sent the flashlight to them where
they will examine it and repair or replace it.