Ah so try a high voltage capacitor wired across the brushes.
Static (pardon the pun) electricity is generated by the
brushes rubbing on the contacts.

--  Paul Lamar ...No rotor no motor.

Paul when not in use the two wires are connected to the brushes only.
Putting a capacitor across them will do nothing, unless one end goes
to ground?
Am I missing something?
Buly

I was wrong.
No your not wrong. Ground it is on both of them. Two caps.
The wires are acting as antennas. Old fashioned transmitter.