Small Engines (Lawn Mowers, etc.): Sears Chainsaw, adjustment screws, rubber gaskets

Question
I own a Sears 18' 40cc chainsaw - model 358.360131. The problem is that its hard to start. When it finally starts, it runs for 10 seconds and dies out. I changed all of the fuel lines, took the cover off the carb and used my air hose to clean out some lint. Using fresh gas, it still wont start.  There are 3 adjustment screws that I haven't touched. Thanks for listening and for your time.

Answer
It sounds like its time for a new carb diaphragm gasket set.  The rubber gaskets loose their flexibility after time.  Fuel with ethanol accelerates this process.  I would recommend a thorough carb cleaning as well.  The symptom you describe is a lack of fuel problem.