There are 4 pressure sensor connectors on the bottom of the unit labeled PSI1, PSI2, PSI3 & PSI4. These connectors correspond to the numbered pressure transducer.
You can remove the pressure sensor connection if needed by turning the circular end of the cord connector counter-clock wise. When it is all the way loosened, pull the connection straight out to remove it.
If you remove and reinstall the sensor connections, take care to attach the pressure transducer to its corresponding numbered port.
All sensors have variation. When the unit is factory calibrated, this variation is taken into account for each port and stored. The Sender uses this to compensate for variation to achieve high accuracy.
To reinstall, ensure the connector is aligned with the pins. It can only be inserted one way. Push it in until the threads can engage and turn the connector end clockwise to thread the connector on finger tight.