The filter on a Hotpoint washing machine is hidden inside the sump hose. The sump hose is at the back of the washing mahcine and goes from the tub to the water pump.
Unplug the washing machine! and take the back panel off. Take the sump hose off of the tub (have a few big bath towels ready to mop up water if you haven't got most of it out - even if you have, there will still be some water in this hose)
You should easily be able to remove and clear the filter. Make sure you refit the hose securely. If it comes off you will have a seriously horrendous flood
Ingy, September 2009