That is a pretty simple carb. There is a small diaphragm under the rectangular cover on the side. They harden with time and need to be replaced. Another comman problem to look for would be the screen on the bottom of the fuel pick up tube that drops into the fuel tank from the bottom of the carb. They often plug up with dirt or rust.
Rick
February 2007
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.