Hi humanoids!

For older pens (cirka 1950), is there a way to do a more thorough (than just "water" / "ultrasound") cleaning of the plastic casing, such as polishing / greasing or whatever, in order to make them flashier? What about the golden nip tip?

Some of the pens I have are pretty scratched from nearly 70 years of active use, and I wanted to do a deeper cleaning every now and then, but all I can find is just "dishwater soap and water", but this doesn't adress polishing the plastic or shining the nip - if these things are even doable.