As you move or strum, the vibration can make the pickup rattle and give off unwanted noises for most players. If the pickup is becoming loose, it should be checked occasionally so it doesn’t become disconnected from the mounting ring or pickguard. The compression or surgical rubber tubing used for height adjust springs may need to be replaced with new ones. Loose or vibrating springs and screws can resonate and cause unwanted feedback. Pickups that are loose and lower in the mounting can also lose tone and output.