Some generic comments regarding electrical contacts.

If you are lucky enough to have gold flashed/coated contacts, do NOT use
an abrasive cleaner.  You'll just take off the gold.

Someone recently stated that he "sanded" his contacts and I shuddered.
Most contact systems will have *some* sort of coating over the copper, tin
or whatever.  But it's apt to be thin (tin costs $).  Why sand it off?  If
an abrasive is still necessary after solvent or chemical cleaning, a
pencil eraser usually works ok.

Of course, heavy current (or cheap) copper/copper/lead contacts are
another story.

As has already been recommended, the silicon grease products do work even
though it may seem counter-intuitive to put an insulating grease directly
onto the contact surfaces.  I understand the metal/metal pressure
displaces the grease at the micro-contact interfaces. And yes a tube does
last a long time; I have an old tube of Dow-Corning stuff which is
probably older than many of the list readers.  :-)

//Jack