Here are the instructions from one of the Briggs manuals:

Disassemble Carburetor
1. Slide jet screen off carburetor body.
Note: Fixed main jet is not a service part.
2. Press in from both sides of primer bulb cavity to
release retainer tabs.
3. Pry retainer out and remove primer bulb.
4. Remove primer seat using a crochet hook or other
type of hook. Ball and spring will fall out, Fig. 4.

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