E10 indicates a difficulty in fill during drying.
I'm surprised that reducing the load lets it work as it's normally a faulty valve that doesn't allow water into the machine.
The normal cause of the fault is the triple inlet valve.
If you post the product number (PNC) from your appliance I'll advise on a couple of checks.
Prefix the number with A to prevent it being crossed out when posted.
OK - will do that tonight. Do you know where I can find the PNC?
If it's a faulty valve, would it stop during the drying cycle?
It should be on a label in the door recess.
Yes, if the valve is going faulty during use, it will stop the machine drying.
I've linked you to a supplier of the valve assembly.
This is the most likely cause of the problem you are having.
Click here for the valve
If the machine begins drying and actually heats then the valve may be failing while it's in use.
If the dryer never actually heats up, then the part of the valve for the dryer is most likely not working at all.
To change the valve, unplug the appliance.
Take the top off.
Turn the water off.
Take the fill hose off.
Dismantle the valve assembly.
Make a note where the hoses fit.
Fit the new valve.
Reassemble the appliance.
Try the machine again.
Hope this helps
Let me know how it goes or if you need more help
For E10 to be displayed during drying the machine has to detect a problem with water coming into the condenser.
The most likely cause is the triple valve.
You can check it by taking the top off of the machine, running the dryer and watching the water flow into the condenser.
If it stops supplying water just before the code appears, the valve has failed.