Unfortunately, this sounds like static electricity.
Leica suggests spraying anti-static spray in the chamber (!). You could
also ground the metal in the chamber using metal wire touching something
metal outside the chamber (the Russian post-doc solution, very clever). We
keep 100% EtOH in a small container (about 100 ml) in the back of the
chamber to reduce static, which I learned from a long ago histonet post, so
I have no idea why it works.
Otherwise, buy an anti-static brush, which I hear exists, but have never
the velocity of time turns her voice into sugar water
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