S2 Steam Turbine 6200 with problem !

Have you tried to turn off the cruise control?

As Chris said, you have to turn off the cruise control. To do that, while the engine is in neutral with the transformer all the way up press and hold the whistle button while you lower the handle on the transformer.

To turn on the cruise you put the engine at the fastest speed you want it to go and hold down the whistle button as you raise the handle on the transformer. This is probably what your friend did without knowing it set his top speed. I've had several customers come in with this problem.

Don't hold the whistle button while moving the handle on the transformer unless you're setting or turning off the cruise control.