Basic Pendulums are simple in shape and move easily. They never emit any harmful vibrations. They are excellent for beginners and can be used successfully to test food and herbs for allergies, searching for answers to life questions, reading charts etc.
With proper care and use, a pendulum will last a lifetime.
The only part that may require replacement due to wear and tear would be the sting or chain that the pendulum is suspended from.
To read more how to replace string or chain...