One of the most important aspects of performing stuck pedal maneuvers as an instructor pilot is to never lose sight of the fact that the pedals are not really fixed. Don't forget that it's only a simulated malfunction. If it isn't working out as planned don't try to salvage the maneuver. Resume normal flight, figure out what went wrong, try it again.
Just like simulated engine failures are simulated. If it isn't working out end the simulation.