quietguy/David wrote:

As far as I know grease is an insulator, not a conductor

==========

You will discover that manufacturers and wise repair people
use grease on many electrical applications.

Watch a pro work on an automobile "no start" problem and you
will most likely see him remove, clean and grease every contact
in the high current starting circuit. Proper operation of the circuit
isdependent upon extremely low resistence and the grease is there
to prevent the corrosion which will ruin that low resistence circuit.

Once again, as others have said, the optimal goal is to restore
the switch to the same condition that it was in when fresh from
the manufacturer, or install a replacement switch which meets
that condition. The OEM switch has a particular type of grease
in it. It is there for a reason. Emulate the manufacturer and do
the same.

Gideon