Hi
Don't replace the springs, they are always floppy-looking. They work against each other. One is put into operation by the throttle lever, the other by a flap which is in the path of the cooling air, and acts like a speed governor. If you remove the starteing rope and its housing, you will see the flap, and you can check if it's free to move. When you get the mower running again, move the lever on the carburettor which is controlled by the flap, and see if the throttle responds.
You should see the springs working.
Jack
Jack Rogerson
September 2007