I own a 77mm B+W Nano Kaesemann Circular Polarizer with Multi-Resistant Coating. It has a small dent in the rim that makes turning it difficult. Can this be repaired, and if so, where? Thanks.
You have two options basically, you can try to repair it yourself or you can go to any camera shop that performs general repairs.
If you try to do it yourself I would recommend a tool such as this Camera Lens Vise Tool.
Keep in mind that CPLs are multiple pieces of glass and quite fragile. With proper it can likely be repaired, but there is a chance of making it worse of course.