Small Engines (Lawn Mowers, etc.): IDLE, briggs stratton, hp briggs

Question
I purchased a "Ryobi" push mower last summer that has  6.5 hp Briggs & Stratton motor.  It has run fine until the other day when I was mowing it suddenly idled way down.  Of course there is no adjustable throttle on this modle mower.  I used it again yesterday and still it is at a very low idle.  I was having trouble with it in thick grass.  The air filter is clean and I put new oil in it at the begining of spring.  How do I adjust the throttle to run at full while I'm mowing?  Why would it all of a sudden just idle down on it's own and stay there?  Any suggestions would be appreciated.  Thank-you,
                       Dave Simmons  

Answer
 Hello Dave:

 Remove the Air Filter. There is Linkeage under the Air Filter that Operates the Engine Speed. It Sounds to Me like the Spring has Broken Or Jumped off.  The Idle can be set here also.  Hope this Helps.

 Good Luck

 Respectively

 John