My washing machine (zanussi zf 400 WN) fills up with water when I run
it. I get the feeling that the pump is broken (which makes a loud
rattling noise when it should be pumping). Have checked the filter at
the front after draining the damn thing a bucket at a time, which was
(nearly) clean but that did not solve the problem.

Assuming I'd rather fix this machine myself than to call a mechanic or
buy a new one, what would be the best way to proceed? Is the pump
probably broken, or just obstructed by something?

Thanks in advance,

Sjoerd