Pebble Motion Problems are when something goes wrong with a pebble, which is a small object made of stone or something similar. It can happen when the pebble gets damaged, breaks, or even when it gets dirty. For example, if your pebble gets dirty it may not move in the way it is supposed to anymore, or if it gets cracked it will not be able to hold up its weight and could crack more. These issues can be fixed easily by cleaning the pebble or replacing it with a new one.