This video, by Light Pole Systems, Inc. is an overview of the steps to clean and repair/paint rusted anchor bolts.
remove the hardware, clean debris with a wire wheel, and paint with rust encapsulating paint.
If the rust is deeper than the paint, the bolt needs to be addressed with a thread extender or new bolts drilled and epoxied.
How to remove rusted nut video: • How To Remove Rusted A...
Rust DR Product Page: rustdoctor.com/
Thread Extender Product Page: lightpolesystems.com/product/...
Thread Extender Promo Video:
Thread Extender Install Overview:
How to Drill and Epoxy Tech Tip: