Kitchen Faucet Won't Turn at Base

Vinegar can remove hard water deposits, and may help. Soak a rag or paper towels in white vinegar and wrap around the base of the faucet. Leave on at least 24 hours, resoaking with vinegar if it dries out. Then scrub thoroughly with an old toothbrush dipped in vinegar. A lot of the scale if not all should come loose. Rinse and let air dry. If you get results but not perfection, repeat. My area has hard water, and my bathroom faucets seem to get the build up of scale the worst. I use the vinegar rag once a week. Hope this helps.