Hi Shannon,
From reading through your previous posts, it seems like it should be a Briggs and Stratton engine you have on your mower.
These engines have a Model Type and Code number stamped on the cowling and it will look like this one in my photo below...

[Linked Image]

The model and Type numbers are important to find your specific engine on the Briggs and Stratton website.
The diaphragm mentioned in earlier posts is found inside the carburetor assembly and, with the Engine Model and Type information, we can help you better identify your actual engine.
If adding petrol to the engine through the plug hole or carburetor helps it start, then it appears to be fuel related, which may also be primer related. That being, the primer is not working effectively.
Can you provide a photo, or detail the Model and Type numbers of the engine?
Thank you.
Daryl

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