Karcher K 3.68M Electric Pressure Washer. Wand trigger Locks Up.

If you are unable to shut off the pressure from the wand, there may be an issue with the unloader valve that is stopping it from switching into bypass mode when the trigger wand is released. The unloader valve is designed to respond to the spike in pressure created when the trigger wand is released, and to divert the flow of water coming from the pump to bypass the pressure hose and flow back into the intake end of the pump. If the unloader valve fails to switch into bypass mode, water may continue to flow out of the trigger wand. This may also cause damage to the wand. If you are unable to shut off the pressure from your power washer, stop the engine and discontinue use immediately. The unloader valve should be removed and possibly replaced if found to be malfunctioning. The inability to stop the flow of high-pressure water from the wand can be dangerous and should be fixed before continuing to use the machine.

Replace wand.

this can be that you need to bleed the system of air or that there is a problem with your trigger gun sticking when you release the trigger.
These are two things I would check before you go into the machine.

The wand (lance) is bad. I went crazy with the same problem. Replaced the wand and now it works normal.

spill valve is stuck and needs to be cleaned and greased common problem....also check all connections for blockage in line

sounds exactly like the problem and the soluition you are looking for.

The wand is plugged.

It sems you have a blockage in the tip. If you get a grain of sand in the nozzle it will act like this. Get a piece of fine wire and poke down the nozzle to free it up.

sounds like the bladder or seals are shot they make a kit for this

check filter in wand and clean out nozzle hole for starters