Todd, I just removed my dust cover & took a good look at the arm after my first cup of coffee. It may be aluminum, & stainless steel underneath. However this is not beadblasted aluminum, & stainless steel in it's raw form.
There is a matte Hard Chrome finish on this arm, & a matte Nickle finish on the Counter-weight.
Vpi keeps Evolving/Upgrading these tables, they probably can't recall what they did lask week? Who did you speak to Sheila, or Mike? Sheila Harry's wife is wonderful to deal with, however she normally yells to Mike, or Harry for the answers. Something may have been lost in the loop???
I would NOT use any type off aluminum cleaner as it is abrasive even in it's mildest state will mar the finish! Also why would you need a cleaner as there is no dirt/stain , your dealing with a surface corrosion issue.
If they refinish it it will add additional weight to the arm IMO. As couldn't see them spending all the time to get it all off? Secondly, sending in the arm would leave you without a source. There has to be some other way to exchange the arm, talk to your dealer.
There is one high performance penetrating lubricant which may be tough to find. However this will not spread/run until the 450 degree range. It will not attract dirt, dust, or lint.
It is called TSI 30I made by American Gas & Chemical Co., 220 Pegasus Ave., Northvale NJ 07647. I would search the web, to find a distributor for a 6oz spray can. I would spray it on a scrap cotton tee shirt section, & gently dab the area until it has a wet-look, then let it sit for 24+ hours. If this doesn't lift the rust, nothing else will! Good Luck!