Many washing machines have a filter in the drain pump. On the front loading washing machines it is located at the front of the machine near the floor. It is recommended to check the filter in the pump chamber once a month. Things like coins and hair clips are the most common things you will find in there. If you cannot open the filter easily its best to give us a call because they are easy to break and a simple thing could turn into something more.
NOTE - There is always a cup of water left in the machine and will drain out when the chamber is opened. If the washing machine is full of water it will come gushing out so be prepared with a towel and a mop. Refer to the instruction manual to your machine for more details on how to perform this procedure.