How can I fix my Karcher K2.94M Pressure washer - No Pressure?

Before it would only work for a few minutes then go off and I would have to wait at least 30 mins or more to get a few more minutes use out of it. But now I dont even get that much out of it.

I hear a buzzing from the motor but the pressure doesnt come on then after a little while the buzzing noise stops as well. The water come through the wand at the pressure from the tap.

So basically at the moment it's no use at all. I am happy to give a go to fix it but I dont know hardly anything about motor so does anyone have any guidance on what to try and how to do it.

Cheers