Small Engines (Lawn Mowers, etc.): Briggs and Stratton Carb on Murry Lawn Tractor, briggs and stratton, hp model

Question
Micheal,
today my lawn mower's throttle stopped working ,except for when the choke is applied.  The engine stayed at full throttle.  It ran faster than it ever had in the past.  I removed the air cleaner assembly and observed the funtionality of the throttle.  It appears to move the rotory assembly on the top of the carb but it doesnt have the effect of shutting down or speeding up the engine.  Just one speed.  The Goveonor seems to be messed up.  i see several small holes on the shaft which I assume are for springs.  I only see one spring attached to the lower part.  I looked for the schematics to see if maybe a spring or something came off but I am at a loss.  Can you help?
Gabe
I have  B and S 12 hp model # 285707 Type 0113

Answer
Hi Gabe,

I suspect that the carb plate or "butterfly" inside the carb throat has come loose.  Remove the air cleaner and look inside the carb throat.  When the rotary disk on top of the carb is moved by the linkage, the internal plate should move and regulate the engine speed.  

Let me know what you find.
Michael