These machines do not have a user-accessible filter. The filter, which incorporates a ball valve,is actually situated in the outlet hose, inside the machine.
This will work perfectly okay for a while, but if you have hard water, use powders or tablets with a lot of filler and have an occasional foreign body included in the wash load it will eventually block up!
Normally this would mean a call out charge and the possibility of being told "you need a new..." which you probably don't!

When the filter gets blocked it will also block the pressure chamber that operates the pressure switch and also push the ball valve up preventing the machine from emptying properly.
The symptoms of this are all or any of the following -
Noisy spin
Inefficient spin due to water in the drum
Juddering and movement when spinning due to water in the drum
Water coming from the powder drawer when filling, spinning or washing.
Water left in the machine at the end of a wash
Machine sticks in mid cycle, especially when rinsing or spinning.

Some of these could also be due to a faulty pressure switch. This can be checked by removing the worktop. Unplug the machine from the Mains! Undo the two screws at the back, push the top backwards and lift! The Switch is the round thing clipped to the side of the machine just behind the powder compartment. It has a thin clear plastic pipe clipped to the bottom. Unclip this pipe and listen! If you hear a click from the switch, the pressure chamber is blocked. The switch is okay! To double check you can suck and blow through the part where the tube attaches. As you do so the switch should click. If you really want to make sure take one of the wires off and put a test meter across the two terminals, set to Ohms. As you suck and blow gently the meter should show if the switch is making or breaking. If it is okay, carry on:

An easy way to see if there is a likelihood of the filter being blocked is to check the waste hose where it is connected to your plumbing.
Remove the "U" trap or the waste connection. If there is evidence of grey sludge in the pipes the filter is also likely to be full of it!
Needless to say, if the pipes are sludgy, clean them out!

These machines are surprisingly easy to work on if you follow the following instructions:
Disconnect the machine from the Electric Main and the Water Supply.
Put the machine in a clear area.
Place a thick cloth, towel or blanket on the floor and gently lay the machine on its left side(viewed from the REAR!)There are TWO very good reasons for this step!(A and B below)
Remove the panel on the back . (2 screws)
(A)You will now find that the concertina hose, the Pressure Chamber and the pump are all easily accessible from the rear and bottom of the machine. You will also see the place where the element is fitted!
There is a large circlip holding the hose to the machine, a small circlip where the hose joins on to the Pressure Chamber and a special plastic clip where it connects to the pump.
To check you just need to undo the large clip and pull it from the bottom of the drum.
(B)Placing the machine on its side means that as you pull this off you will not have water pouring out of the drum over yourself, the floor and any electriclal connections!!
Inside the pipe you will find a "ping pong ball" and a conical nylon fitting. Remove these and check to see how badly this is blocked. If these are covered with sludge you can reckon the pressure chamber and pipe to the pump are also blocked!
Remove the second smaller circlip to the pressure chamber. If this is blocked you will be able to see straight away.
This chamber is really just a larger nylon pipe that joins on to the tube to the pressure switch. It can easily be detached from the tube by gently pulling the two apart. There is a very small cable tie clipping them together but his should be able to be re-used. The tube to the switch is clipped to the drum and this can unclipped if the tube has also filled with gunge or water so it can be cleaned.
The third clip is a different type and this has to be gently opened with pliers. Lever one part to the left and the other to the right to unclip the serrations. When this is refitted you just need to push the clip tightly so that the serrations hold it closed.

Once this clip is off you can remove the whole hose and pressure chamber for cleaning. You may find it needs gentle scraping or an application of vinegar or limescale remover.
Invariably you will find that buttons, hair, threads, foreign objects, sludge and limescale will be included. On my friend's machine we found a valuable gold bracelet she thought she had lost. On mine I just found buttons!

While the hose is off take the opportunity to see if the element is heavily scaled and to check the inside of the drum!
Once the filter has been cleaned, refit it. It has a raised rectangle on the rubber which fits into a similar hole on the plastic filter.
Don't forget to replace the ball!
Everything is now just a reversal of the removal instructions.
This whole job should only take half an hour or so, depending on how long it takes to clear the muck and limescale from the filter!!