Where can I download a service manual for my Zanussi Jetsystem ZWD 1000?

Where can I download a service manual for my Zanussi Jetsystem ZWD 1000, my machine is not drain water 2 or 3 times per one full cicle of wash, and the drain pump work good? I am the second user of this machine, perhaps configuration of drain system was changed and air can not go out from the drain pump. Could you kindly help me to fix my ZWD 1000.