You might be able to tin the sheetmetal using 60/40 solder and a big
soldering iron or a hotplate or something.
That would solve the problem for good.

(Although light brushing and painting with some acrylic laquer would
probably suffice to eliminate any issues during your lifetime).

ST

On Tue, Jan 26, 2016 at 12:12 PM, Tothwolf tothwolf@...
[TekScopes] <TekScopes@...> wrote:

One other issue I noticed which I forgot to mention in my posts to the
list last year was the metal bracket that the focus control is mounted to
was showing signs of tin whisker growth in all 3 of my 2213 scopes. While
I had it and the potentiometer removed so I could replace the 6 1M ohm
resistors, I lightly abraded the surface of the bracket to knock the tin
whiskers down, but I know if I leave the plating as-is, they will without
a doubt eventually return. I am considering using electrolysis to strip
the tin plating and then replate the steel bracket with nickel. You can
just barely see eruptions in the tin plating on the right side of the
bracket in this photo, but up close, 3-5mm long tin whiskers were pretty
easy to see.

http://strudel.ignorelist.com/~tothwolf/photos/Tektronix_2213/Tektronix_2213_3/1600/IMG_9288.1600.jpg