Small Engines (Lawn Mowers, etc.): Problem with Murray mower running, briggs stratton, murray mower

Question
Mr. Bridgers,

Sir, I have a Murray 20 inch lawnmower with a a Briggs-Stratton 4.75 engine.  I am in the military and recently moved.  During the move I lost my pamphlet on the lawnmower and engine.  When I tried to run the mower the other day (with a full tank of gas) it only cut about one strip in the yard before it just choked and died.  I have not replaced the air filter, spark plug, or muffler on this engine in 3 years.  Do I need to replace any or all of these?  Also, if I need to replace the muffler, how do I do that (I can't tell by looking at the mower how it is removed).  Finally, what type of oil do you recommend I use for the mower?  Thank you for any assistance you can provide.

Sincerely,
Tom Finneran

Answer
 Hello Tom:

 The Air Filter should be Cleaned Every Year Before Using the Mower and the Oil should be Changed at the Start of Every Mowing Season and Changed Every 20 to 25 Hours After that. I use SAE 10W30 or SAE 30 Motor Oil. The Muffler is Screwed into the Engine Block and it is Best if the Engine is Hot when Removing the Muffler. A Pipe Wrench can be Used to Turn the Muffler Out of the Block. It sounds like Trash may be in the Carburator. What does the Engine do when you Try to Restart it? Hope this Helps. Let me know what Happens, Please.

 Good Luck

 Respectfully

 John