hi goaticus,
Give me a minute just got my wires crossed at this end...
I will repost.
EDIT:
Here we go.
Look at this image, set up the LM3914 this way.
To Calibrate the sensor amp I would use a 100R variable resistor to simulate the tank sensor.
At first set both the Zero and Span pots to 50% rotation.
1. Set the sensor sim resistor to 77R and adjust the Zero so that LED#1 lights.
2. Set the sensor sim resistor to 7R and adjust the Span so that LED#10 lights
repeat this from line number 1 until the LED's are LED#1 for 77R and LED#10 for 7R
OK.