At some point the thread for the hot water line was damaged and would leak if the machine ran a warm or hot wash. I tried to cut the thread back to remove the damage but it was just slightly too short to seal.
I ordered the valve and had it overnighted, as the washer had already been out of service while I replaced the door seal.
Unplugged the machine, turned off the water and disconnected the hoses, removed the top and replaced the valve. Very easy repair, my only mistake was not wearing gloves so I cut a finger when I pulled the water hose off the valve - the inside of the frame is sharp.
The wires connecting to the valves can't be mixed up on my machine, the harness won't allow it unless you've cut the wire ties. I still took a picture on the phone though, just in case.