Probably a good bet it's the fuel pump diaphragm. A good mower shop should have them in stock, probably around $2.00. I get them by the 10 pack off ebay usually for +- 75 cents each. Pays to have them on hand if you run ethanol laced fuel. Alcohol makes them stiff and won't pump fuel.
It's behind a rectangle plate on the side of the carb. Most you have to remove the air filter housing, and the rubber tube to get to them easily. Old screw were small Phillips head, new one's are like a #15 Torx. Remove plate and pull off. When removing diaphragm, be careful because there is a spring behind it and a cap for the spring to push against the diaphragm so as not to damage.
For a first timer, probably a 25 minute fix if you have the part & tools. After doing 15 or 20 of them 15 minute fix and that's taking a smoke break.
Remove the old one and take it with you to match a new one. It will probably be somewhat stiff. The new one is really limber and will fold over in half holding on to one end. There are holes that go over guide pins, so it's an easy fix.
