Advice on stripping paint and restoring a 1950's aluminum lamp shade?  

I have a Greta Grossman Cobra desk lamp, which I'm 99% sure has been repainted at some point.

The lamp is black in in it's current state, but there are a few places, where the black paint has come off and I can see a greyish green color underneath. I belive this is the original color.

I have several other Grossman lamps, and the paint finish is not as smooth on this lamp as the others, which is another reason why I believe it to have been tampered with. My guess is that the new paint job was done using a regular black spray paint.

Does any of the dealers and collectors on the forum have any experience in stripping just one layer of paint? If possible, I would like to remove the black paint without damaging the original green and I have no experience in what products to use?

I'm thinking this should not be a completely impossible task, since the black color has already come off at a few spots and the green color looks unharmed underneath. Also, the original paint on these lamps is usually much thicker than the black finish, so I guess they must be powder coated (if this was a technique used in 1950?) and therefor more durable than the black spray paint?

Of course, it's possible that the black paint is covering some terrible scratches and losses to the original paint, but I'd prefer the original finish, with some patina, than a badly done repaint.

Any ideas?

/Alex