Hotpoint Ultima WD860 washer/dryer error f-05?

Hi,
I have error f-05 showing on my machine.
I did uncover the bottom plate to unscrew the filter at the front but it is covered with a red plastic disc showing a hand with a shock bolt across it. Doesn't this mean that I shouldn't be touching it, or is there some other method of draining and cleaning?
Please help.......Helen.