Water curtain control sensor…
Hmm….
Are you referring to the switch on the curtain that tells the unit when it dropped ice or if its full? Or are you referring to the sensor detecting if the water sump is full or not?
Or am I completely off and you are talking about something completely different.
IF its a reed switch (a magnetically engaging switch) or a micro switch or any type of switch that goes from closed to open, it can be verified it its bad enough by ohming them out and that will tell you if its bad.
To me it sounds like you got some kind of harvesting error going on so the unit only makes one batch of ice and then stops producing ice, this can be either due to the harvest error or the switch is in fact bad and the unit thinks it’s full.
“it is not the electric” I Am slightly confused about that but I think the above should give you something to look for. ITs not very common switches just “go bad” and if they do, they can be verified to be bad and then there is no question.