I have diagnosed the problem that it is not filling the tub properly. If I manually fill the tub all appears to work Ok. I have checked the inlet solenoid and it appears to be ok. The tub is partially filling.
Any suggestions as to what the fix is?
Your diagnosis is wrong. According to the Baumatic book for that model, the E3 error means it is not heating the water. Check the element and the thermostat.
