said by shdesigns:
Might be worth ordering a new diaphragm and gasket.
Done, no change, and another $4 down. I thought about replacing the tank and carb, but that would cost me at least $70 when the whole mower was only $150.
There's also a new symptom the last few times I tried to start it. Now the mower usually starts on the second pull when it used to start on the first ("start" meaning "run for three seconds and die"). Is that a clue?