Small Engines (Lawn Mowers, etc.): RPM dropped, sears craftsman, carburator

Question
I have a Sears Craftsman push mover. While cutting my lawn, all of a sudden the RPM's seem to have dropped by about half. The engine still runs, but it seems to be tearing the grass rather than cutting it.

Answer
 Hello John:

 Send me the Model Numbers Off Of the Engine. They are Normally Located on the Blower Housing(metal engine cover). With these Numbers I can View a Breakdown of the Engine and See the Type of Carburator and Governor System is on this Engine. Thanks.

 Respectfully

 John