fg_throttle = Serial.read(); // this doesn't seem to read the value correctly
The Serial.read() function reads one character/byte from the serial monitor. If you are sending a value between 0 and 1, that code is going to read either a '0' or a '1", which you will see are NOT the same as 0 or 1.
When you multiply '0' (48) or '1' (49) by 10, you get 480 or 490, not a value between 0 and 10. Somehow, I doubt that you can display 480 or 490 on your single digit display.