I recently purchased a large amount of servos for use in a project where each servo would have an arm fitted that would strike a bell.
Maybe a servo is simply the wrong thing... For example, a door bell uses a [u]solenoid[/u].
Or you might want a regular 'ol DC motor, possibly with a couple of limit sensors/switches so your software can know when it's gone far enough.
A typical servo application is to control the steering on a remote control car. You specify the angle, and the motor moves to that angle. Servo motors are geared-down so they tend to be fairly slow. If you want to slow it down more, you can slowly increase/decrease the angle. If it's jerking back-and-forth, something is wrong.
A stepper motor can rotate the full 360 degrees in steps of 1.8 degrees. (Or, you can "microstep" them to move a fraction of a step). Usually, stepper motors need some sort of limit sensor to find their "starting point" Stepper motors can be fast (or slow, obviously) but usually not as fast as a DC motor. For example, the movement of a printer head is usually controlled by a stepper motor. There is a position sensor to find "home" when the printer is powered-on or reset, then the firmware just keeps track of the number of steps back-and-forth so it knows where it is on across the paper. Another stepper motor may feed the paper.