I noticed I was leaking diesel fuel form cylinder head number 4 ( last one closet to the battery). After reading up on it more, and looking closer at the problem it looks to be leaking from the last leak off tube that has been deleted with a screw in the top of the rubber fuel line.
My question is should the leak off tube be plumbed back into the return line after the last cylinder? Or does this mean that the injector is not working properly and needs to be replaced and the leak off tube is installed correctly?

Thanks