Most washing machines have a filter that is accessible from the front of the machine.
Iif you have one of these machines then you should check this filter once a month to clear out any debris that has collected there such as coins, hairclips, small toys.
To check simply open the flap and unscrew the filter. However you must be careful to screw it back in properly to prevent cross threading and leaks afterwards. If you clear your filter regularly it can prevent problems such as smelly machines and drain/spin faults.