So you’ve cleaned your tanks thoroughly and the tank level sensors are still not functioning properly. Looks like they have stopped working and it’s time to replace them.
To do this, first figure out the part number for the part that needs to be replaced. You may need to do some in-depth online sleuthing to accomplish this. Then order the part from either the manufacturer, or an after-market supplier.
From here, the steps are going to differ largely with each type of sensor. I suggest setting up a video camera and recording yourself methodically taking apart the system. Reference the internet and YouTube tutorials when you hit a tricky spot.
Then, once you’ve removed the broken unit, play the video you recorded, and follow those same steps in reverse. I’ve been a carpenter and technician most of my life, and this is an almost fool-proof way to ensure you can reassemble a system after taking it apart.