Hi and welcome the forum
Can't really answer the auto choke part, but if it had a auto choke, it would not probably have a primer. Both a choke and a primer do the same thing, get more raw gas into the cylinder.
I have a 6HP Lawn Boy push mower, that only has a primer.
Now I also have snow blowers that use both a primer and a manual choke. Of course the are for cold weather, which makes harder to and keep running
Here is the JD site, try and look it up for parts:
http://jdpc.deere.com/jdpc/servlet/c...30105293566#:4
BG