Chuck Harris wrote:

I have gotten radios that were used by hams that had chassis that
were stained yellow brown from the tar and nicotine. There is no
amount of airing out that will make that go away. With them, the
only answer is scrub, scrub, scrub. The cleaning solution comes out
as brown as grasshopper spit.

That's a different problem altogether. In that case, 409 is VERY effective
at removing the gum, as long as you keep it off of phenolic parts. It will
etch bakelite very quickly.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."