Need some help with Black Tank Sensors

[ramair]

This is not the standard issue with the sensors reading full all the time. In 2013 replaced our sensors with the Horst Miracle Probes and they have been working great always accurate, This last time dumped and flushed our black tank and now they will not read the 2/3 or full. It will read the 1/3 level and have looked at the wires at the tank and they are still connected. We have not moved or anything, so was wondering if the sensors go bad?
Also once it warms up I plane on gaining access and removing the wires and see if I connect to the 1/3 if they will read. Ordered a new set of probes just in case (40 bucks)
All other tank sensors are reading correct. If any knows the wiring from the tank to the panel would be greatly appreciated. Just trying to gather information before I tear into it. Thanks in Advance...

[doc73]

I am sure they CAN go bad, but I would be more inclined to think a wire issue. Make sure the connectors do not look corroded up it does not take much to make them get goofey.