I have the black choke holder pulled out and have taken a razor blade to the box around the seam on the end the cable goes in. Half of the seam will come apart but the other half will not. It is the half where the cable goes in. It seems like it is going to come out but that one side just seems completely stuck.

 

Spray some PB Blaster,WD40,etc and let it sit a little while.It's just a plastic plunger and spring.You may have to loosen the lock nut on the choke adjuster on the carb and tun the adjuster in to get enough slack to pull the choke plunger out also.

 

Thanks. I have pried on the thing with a screwdriver as hard as I can. Even so hard it broke one corner of the edge of the box. It has been on there for 20 years I guess it won't give up the ghost. I will try WD-40

 

Did you remove the lever by pushing out the roll pin? It should pop right off once the lever is off.

 

The reason I need to take it apart is because the hole in the plunger cracked and the pin came out and the lever came off in my hand. 20 years old on a cold morning. The back of the box absolutely will not come apart. I can pull on the plunger and it still chokes fine. I don't think anything inside is actually broken.

 

I believe there are clips on the back side that hold into the housing. Try inserting your blade between the bottom and housing to loosen it. The housings are able to be found on ebay, usually with the cable if it ends up not being repairable.
You could try slitting the bound side of the housing to carefully pry up.