Karcher prssure washer motor will not start

indicates a blockage at the wand jet

it is not uncommon that the switch is bad? if the switch controls the pressure telling it their is water and to start working? then i would just replace the switch.

I fixed mine works good easy too watch my video step by step i put it on youtube
http://www.youtube.com/watch?v=UFXSLOBL0Mg

The little white thing is most likely a capacitor, and only AC current affects this it blocks DC. These don't often fail, and if but if suspect, then replacement is the only way to tell?
You need to check at the actual terminals on the Motor to see if the power is getting there, it should be present at one side of the motor, the "Hot"side, and the other side or "Cold"side will contact to the Neutral wire, to complete the circuit. It is a very basic circuit.
You also need to check the motor is OK, While motor is disconnected, use a meter set to OHMS, and measure across the the motor's terminals, you should get a lowish Ohmic reading, if it is Open circuit, high Megohms, then either the Motor has "Blown" or the embedded protection fuses inside the motor have, either way the effect is the same the motor must be replaced. This is often what it is.
Below is a exploded diagram manual that may help, it's not all in English, but gives one a good idea.
http://www.pressure-power-washer.com/pdf/karcher/5955-6440.pdf

I don't know either. Anyone got an answer?

replace the fuel carburetor filter and, or, your fuel tank filter

The pump that connects to the motor could be bad/and or loose

Hi
don't know if this will help, but when I use mine, to start the pressure up I have to turn the nozzle to fine spray then turn it to the power spray and it works every time, shouldn't have to do this but I got it for nothing.

my 620m has a problem when i press the switch on it has no pressure and the pump sounds like it is not kicking in .... plese help !!!
steve ..