There are two kinds of "stuck:" If you hear the blender speed up suddenly, then you need to stop, give it a little stir, and start again from the lowest speed while the liquid gets moving again. When you see good movement, you can slowly increase the speed. If something is physically blocking the blades from continuing to spin, your blender may trip your breaker. If this happens, unplug the blender, turn the breaker back on, and then carefully press the safety buttons on your outlet to reactivate. Then stir up your smoothie so the obstruction moves, and try again. If the obstruction is large (e.g. more than 1 or 2 frozen strawberries stuck together), you may need to physically break apart the mass so it doesn't damage your blender and outlet.