iDos dispenser always low

[Renoir]

VarioPerfect Serie 8. IDos dispenser is showing low detergent all the time. Even after filling up to max. It began so after I accidentally dropped too much detergent for the drum clean cycle. Foam was coming out of the drawer. Is that the dispenser fried or anything else? Or could it be reset somehow? 

[Whitegoodshelp (Andy)]

Has the foam gone away now? It's possible something was affected by foam (and therefore water) getting into somewhere it shouldn't. But I would expect the sensors for determining how much detergent is inside the detergent containers would be on the containers themselves.

[Renoir]

The foam incident occurred about two years ago. I just get annoyed from time to time still that it’s not working. Everything else seems to be working. Even the level indicator for the softener compartment which is right next to it. There are two metal rods that touch liquid and by that make a chain (or whatever it’s called correctly) which means there is enough liquid in the compartment. When the liquid level drops and the two rods are in the air it signals a low level. At least that’s what I understand.