1 gallon goes pretty far on these cars,(you are putting both the supply and the return line into the 1gallon tank right?) drop the tank (ain't it easy on the TD's?...) and take it to get steam cleaned. you will need to flush out your lines to the tank, and now is a good time to replace all the rubber connectors on the fuel lines...
www.dieselgiant.com has a nice DIY for this. email phil at the buy parts link above. he will have a set of replacement hoses including the "cigar hose" on your doorstep in a few days! (overnight if you are close to one of his depots) have fun!