Zanussi wjd 1294 dryer problems?

I have a Zanussi WJD 1294 which washes fine but has problems when it comes to drying. When it goes onto the drying cycle, either pre-set after the wash or manually it will dry for a few minutes then clicks to the end of the cycle. The clothes are warmed when they're removed but obviously not dry as you only have three or four minutes of the drying cycle. You can hear the pump working so I don't think it's that, does anyone have any ideas as to what it may be?

Many thanks in advance.