Simon I presume you have a ZWD1480W? A washer dryer?
Can be three things ( actually it can be several more! ) and usually they`re fairly abstract causes such as it is the dryer element to earth which doesn`t take out a trip switch but it temporarily messes-up the pcb by back feeding through neutral, 2nd possibility is the tacho magnet comes loose and tends to push out the tacho coil out of its housing; the tacho coil can be found at the back of the motor and thirdly the wash heating element is either to earth or one wire has fallen off-this 3rd one is not that likely. Very rarely is it ever the pcboard that causes this fault.