HI, Not sure if you've received any replies yet. I just fixed my 742 and I'm guessing your 440B might have a similar system. My problem was a split in the pickup tube in the fuel tank. The machine would stop working unless I filled it up with gas. The old pickup tube in the tank had a split in the tube from the tank fitting to about half way down. The diesel and gas 740 series use the same fuel system and can have the same problem. THe only difference with the two fuel tanks is the gas does not have a fuel return line as the diesel would.
Hope that helps!