I believe I have a diesel leak coming from the middle injector(?) and am wondering what type of seal may have failed. O ring? Crush washer? Something else? I've attached pictures for reference.
Try spraying with brake cleaner to get it super clean to make sure where the leak is,hard to tell from the picture.
Looks like there is fuel all the way at the top, where the line and nut thread onto the injector. If it's like a Cummins, it's a tapered, compression fit. Snug the nut a little and clean it and see if it leaks anymore.
Are you sure it's not coming from the injector return lines? I would replace them first as long as the injector high pressure line is tight.