Mine was doing the same thing last winter too. I purchased a proper choke and carb cleaner from an auto parts store, took apart what I could and sprayed everything ( use an old toothbrush to remove heavy build up). Been fine since then.
Cable. Choke moves free if I pull on the cable right next to it..its how I have been starting it recentlyI assume it is cable operated? Is the cable causing the problem or is it the choke portion of the carb'?