Small Engines (Lawn Mowers, etc.): Ryobi line trimmer/zama carby, ryobi line trimmer, throttle shaft

Question
I can start the engine but it revs highly and I cant reduce the RPM. Seated both L & H needle and backed them off 1 and 1/4 turns as specified. Have tried small adjustments to both needles but nothing seems to reduce revs. Have also backed off idle screw without success. Do you have any ideas please?

Answer
 Hello David:

 Remove the Air Filter and Check the Throttle Plate. Has the Attaching Screw Come Out and the Plate is Stuck in the Open Position? Is the Throttle Cable Working at the Carburetor? Move the Cable and Watch the Carburetor Throttle Shaft. Is this Shaft Moving when you Accelerate using the Throttle Trigger? Is the Fuel Cap Venting the Tank? Remove the Muffler and Ensure the Muffler and Exhaust Port are Not Blocked/Restricted with Carbon. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks. Be Safe.

 Good Luck

 Respectfully

 John

 PS: Happy Thanksgiving and Merry Christmas (:-))