You can go 3rd party shop or you can go back to nikon. 3rd party shops for newer cameras may be iffy since most of them have techs that used to work somewhere but may or may not be up to date with newer camera. Normally if a camera works there is no need to service. Unless you shoot say 10,000 or more frames per month, preventive maintenance is probably unnecessary, and mo pro do this because they shoot in large frame counts and well maybe have better tech service. Here techs are relatively careless even at camera makers workshop. I once saw when my lens was being converted to AI how they handle the lens - rear element cap off - the lens was place on the work table rear element down before I could do anything it was pickup with a swiping action - yes there were a couple of fine scratch marks from this. It should have been pick up in a vertical lifting motion.