Milky white deposit on cantilever/stylus of NOS Signet TK10ML, still in original box, etc.

A friend of mine has acquired an NOS Signet TK10ML.  The cartridge was part of a huge inventory of "stuff" that he purchased from a defunct dealer.  He notes that the stylus is completely obscured by a deposit of a "milky white substance".  Has anyone got any idea what this could be and how to get rid of it without damaging the cantilever and/or stylus?  Thanks.
I haven't examined the problem first hand, as my friend lives a few hundred miles away from my location.

My first inclination is corrosion. but I'm not sure how boron corrodes, I know aluminum will leave a white powdery substance behind for example. If its that old it will need to be rebuilt regardless as the suspension can-will decay over time.

one thought is to get a high power magnifying glass or usb microscope and take a look. Look to see how far up it goes on the cantilever if its all the way up into the motor assembly (coil) then its probably going to need a rebuild or possibly its now duff.

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I think if he looks at it with a 60x loupe that may be helpful and tell him a lot. He can order one on Amazon or eBay for about $10.

Sounds like some sort of environmentally caused corrosion.

I was convinced that my sample has beryllium cantilever. By

beryllium one can see something like ''peel off'' (by paint). I don't

believe beryllium oxidise. But my my check today I think that Lew

is right because the cantilever looks like boron (aka ''black'').

For the function  only the stylus is relevant. Diamond

certainly does not oxidise. So cleaning the stylus in ''ordinary

way'' will be sufficient. For ''esthetical reasons'' one can try to

clean the cantilever also but should use soft brush.

By beryllium cantilevers in particular those which are ''tubular''

those (wands) are very thin. So the risk of breaking real. My

idea is to use thin layer of glue in order to keep the ''peel off''

parts together and increase the rigidity of the cantilever.

I have been trying to post some responses without success.  So far as I can tell, boron is relatively inert.  It does not oxidize readily, therefore.  The item was in a factory sealed box or package all this time.  I am wondering whether due to changes in temp and humidity, the deposit comes from the plastic component of the factory container.  This jibes with the fact that my friend obtained a used TK10ML along with the NOS one, and the used one has no such deposit on the cantilever/stylus.