I have a Karcher pressure washer 620m and the motor will not come on. ?

Hi guys. Rose here so be gentle with the terminology as I have read a previous post on fixing this problem and got lost in all of the techno stuff. My Karcher has power as the green light comes oin when switched on. There is no blockage in the systen=m as the water comes through under normal pressure. However the motor will not switch on. I have read about the micro switch which might have turned the motor off, is this easy to fix or should I drop it in to be repaired. I am pretty savvy with repairing things if it is explained to me in Ladybird book fashion as I am not an engineer. Can somebody help as I dont want to have to pay the €65 for a registered technician to have a look at the machine to just flick a switch. Thanks so much in advance.