Choke plate does not close fully?

I have a 4hp B&S Quantum lawn mower. It's old but runs well. I have had difficulty starting it for about a year. If I spray starter fluid in the carb or the cumbustion chamber it starts right away and runs until I shut it off. I noticed that the choke plate does not fully close when the choke is engaged. When I pulled the air cleaner and assembly off, the spring that should close the choke plate seems to be attached improperly. Is there a diagram somewhere that shows how it is supposed to be assembled?