I've used over cleaner on a chrome part that someone painted. Spray on, wait 5 mins, wipe off. Depending on how thick the paint is might need a couple of goes. Didn't affect the chrome at all.
Or try a hardcore paint remover spray from your local hardware or car parts store. Not sure what it would do to the aluminium underneath though.
Maybe even just sand the all the parts smooth (not removing all the blue finish) and spray your black over the top?
The blue paint is the factory Trust/Greddy finish in case you didn't know.