don't sent for polish, unless your watch need service, do it together.
as you said, have to take out the movement, alway never open the back cover unless only need services.
i bought a used ball hydrocarbon sent to polish, less 3 months watch stop, sent for repair, the watch repairman said
movement dirty need services, next time dont polish only, do it together service & polish.
you can do it yourself polish, use basso or toothpaste polish after that use car polish smooth it,
that what i do, very good result, give it a try.