Chokes get stuck commonly in guns that are poorly cared for where they can get rusted in, or where over zealously tightened and rarely changed.
Regular gun oil will suffice, or grease. Take your chokes out and clean them every time you break out the rods, a light wipe of oil into the threads, finger tighten and you are good. Sage words from my local gunsmith when I was a lad, never had any problems since.
My Lanber gets a bore snake and wipe down every time fired, with a proper rod and brush out and oil down every 150 shells or if storing for longer periods. If your gun gets wet you should always give it a through drying, clean and oil, including chokes and threads.