Grey sensor showing 2/3 full
I know it's a common issue however I can't seem to get the sensor to read right. The sensor keeps on reading 2/3 and when it's actually full it does say full, when it's empty it reads 2/3. I tried using dish detergent and filled up the tank and let it sit there hoping it will clean the sensors but it didn't.
Has anybody had any success in trying to clean the sensors in the grey tank? If so what did they use.