The zinc plating on the steel components of Hammond organs sometimes can grow metallic fur or ''dendrites''. I have no idea what the actual growth mechanism is (if you know, please enlighten us!). Heat and humidity can tend to speed the growth of dendrites.
Even scientists don't know the actual reasons for dendrite growth. The gravity induced convection makes it impossible to track the dendrite growth. Therefore they made an experiment, that flew with the space shuttle:
[Isothermal Dendritic Growth Experiment (IDGE)|http://microgravity.grc.nasa.gov/expr2/idge.htm]. One thing is known for sure: the solidified zinc surface shows the dendrite structure already. And the fresh zinc surface is chemically active. If humidity is high, a zinc solute can occur, which leads to the growth. A way out of this is to plate the surfaces with chrome to passify the zinc. A simple lacquer layer does the same.
+
+Other pure metals (and some alloys) can also grow whiskers.
+NASA has some good on-line resources on
+[tin whiskers|http://nepp.nasa.gov/whisker/]
+and [many other kinds of whiskers|http://nepp.nasa.gov/whisker/other_whisker/].
+There is some [concern|http://www.fortune.com/fortune/thisjustin/0,15704,1012859,00.html]
+in the electronics industry that the elimination of lead from solder ---
+motivated by environmental and health concerns --- which is currently underway will lead to
+problems due to the growth "tin whiskers" in all kinds of electronic equipment.
+
In any case, the ''dendrites'', being metallic and therefore ''conductive'' can cause all kinds of mischief in your organ. Dendrites are often the cause problems in the vibrato [Scanner], and the [Vibrato] switch assembly, where they cause MotorBoating, or choppy vibrato; and also in PercussionSwitchAssembly, and in the manuals, where they can cause the [Percussion] to misbehave, or can cause strange ''hums'', funny cross-talk like sounds and other wierd symptoms.
Dendrites can also grow in/on the swell capacitor (where they'll cause terrible noises.)
