Hoover PE235 - Stops at rinse?

Have a hoover Pe235 Auto washing machine. Its a cr*p machine, never have like it, but anyway to make matters worse, it now doesnt complete the wash cycle.
Its got one of those manual trimer knobs you turn. I normally always use wash cycle number 4 - for cottons at 40degrees. As the wash cycle goes on, it fills up and the drum goes round and the the knob turns slowly as it works through the cycle as expected, but then at the rinse stage, it just sits there! Theres still water in the drum and the door remains locked. I have to turn the timer knob to OFF to get the clothes out, but then all the soapy water comes pouring out too. Does anyone know why its stopping in mid wash cycle?