Hi David

It's in one of two places. Either at a fitting connection or one of the tubes that fits overtop of the brass lines coming out of the compressor cover. I would suggest that you start by replacing all the fuel lines under the cover and ensuring that they are fully seated in the fittings. Make sure that you cut the ends of the tubing square. If it still leaks, then it is either the fuel or bearing lube line that is leaking, most likely the fuel line. If it is one of these, the you need to replace the lines with either blue or yellow tubing. You can use the clear, but I have best luck with the blue festo line. Since you've already replaced these lines once, you know how tough it is. What I do is cut the tubing to length, put it on an allen key the slightly stretches the tubing and place in HOT water for about 5 minutes. Then I quickly take it off the allen key and push it down on to the tube all the way to the aluminum. The other trick I use is to but a small bead of thick CA at the base of the tube where it goes into the aluminum and push the tubing into to create a seal. You may also want to check the two elbow fitting to make sure that the teeth and seal are not bend out of shape. If they are, then replace the fitting as well.

Good Luck,
Ed