Water freely runs through machine and lance, when power is turned on it has no water pressure. I have tried removing head and was covered in oil? The question is:- how do I refill oil chamber? how do I clean any valves that might be stuck that stop the machine from producing water pressure?

merlyne, December 2015

Yes, I found that info already and it helped me strip the unit down. Have since found out it was not oil but cleaning fluid that leaked out when I loosened the head. Even though water flows through machine and the motor works it does not pressurize the water. So will have to strip it down again to find the problem.
Thanks for your help.

merlyne, December 2015

Extensive parts diagrams available here:
http://septimus-spares.co.uk/cold-pressure-washer/karcher-home-garden/k-620m/

I BELIEVE this is the section that switches off the motor if it thinks the washer outlet is not open (Note I said it thinks the outlet is not open. It may be faulty and not letting the motor cut in when the trigger is operated)
http://septimus-spares.co.uk/cold-pressure-washer/karcher-home-garden/k-620m/excesscurrent1/#parts

I BELIEVE this is the area that would be lubricated - the gearbox:
http://septimus-spares.co.uk/cold-pressure-washer/karcher-home-garden/k-620m/transmission28/#parts

Available as a PDF here:
https://www.pressureparts.com/mmDEV/PDF/karcherparts/K620M%201.973-680.0.pdf

Of course, you'd have done a search and found all that anyway - wouldn't you? Took me about 2 minutes.

XX, December 2015