Both of these probes are no longer reporting correct results.

Temp probe reports 80.7, chiller reports 74 and mercury thermometer
Reports 76.

Salinity probe was reporting 40+ so I calibrated it. It was correct for a few days, then dropped to readings in the low 30s, then instantly switched to reporting 45-49. Confirmed accurate salinity via refractometer. I’ve repeatedly checked for microbubbles

What’s going on and how do I resolve this?