Nucleogenesis

I have a 1984 RX7 GSL with the stock Nikki carb and all the emissions junk, and I'm trying to figure out how to get the choke to close all the way. The magnet and cable are all in good order, but when the choke **** is pulled fully, the flap in the carb doesn't close all the way; just from fiddling around, this is the difference between ten minutes of cranking and firing it right up. With the choke **** pulled, the flap is loose with about 1/8 inch of free play, and weak spring resistance everywhere else.

I tightened the cable, but it appears to make no difference. The spring that is visible on the side of carb appears to just pull the **** back in when the magnet is released. Are there any other springs that I should check, or an arm buried somewhere that might be loose?

Any suggestions would be appreciated, thanks!