AVS Choke Doesn't Work

First thing I'd do is disconnect the thermostat and make sure the linkage on the carb is working freely

To do that, disconnect the thermostat, and while holding gently against the choke butterfly, opent the throttle slightly, at which time you should be able to push the butterfly completely closed with no effort.

RELEASE the throttle, which should bring the throttle down on the fast idle step. You should now be able to push the choke easily closed, and when you open the throttle slightly, the weight of the fast idle cam should pull the choke butterfly completely open.

All this should work freely and easily, with no help from your fingers.

Next, maybe with a second person, hold the choke closed and start the engine, without dropping the throttle off the fast step. The choke pull-off diaphragm should now suck inwards, and this should make a definate "stop" which you cannot push the choke butterfly past. That is, the pull off sucks down and opens the throttle butterfly by some amount, the specs of which are in the shop manul.

If all that checks out, you can then concentrate on the choke thermostat.