I've been searching for a non-destructive (to paint and chrome) rust remover for a while, and wanted to share a good find - "Evapo-Rust:"
I've only just started experimenting with it, but so far it appears to do what the manufacturer claims. I soaked part of a very rusty 1930s fork in the solution with the following results:
The paint seems unharmed, although it would be pretty hard to tell for sure. At least I can get a better idea of what the paint looked like.
This is not a product endorsement - I don't have any connection with the manufacturer and I'm certainly not guaranteeing anyone else's results. But if you give it a try let me know how it works for you.
Portola Valley, CA