[Elecraft] cleaning a key

[J F]

Hi,
there are several products that will work. As I
recall, all of the military keys were silver coated
(tending to oxidize black). A dilute solution of
ammonia in water will clean most of the oxidation. You
can also use a toothbrush and baking soda. 
There is another product called "simichrome" that is a
good polish, also useful on plastics. Silver tarnish
cleaners are also usable.
If you are attempting to keep this in "collectable"
condition stick with the ammonia and simichrome.
Make sure you clean, flush and dry the contacts real
well, any buildup in these two spots will cause
irratic operation.
Hope this helps.
Julius
n2wn