Is it normal to be able to wiggle the fuel line to the injectors by hand?
Return line ?
Yes, that's the return line on pencil style injectors. It's just a rubber grommet inside that compression nut, not a brass sleeve. If it's not leaking, don't mess with it. If it is leaking, get new rubber seals.
It's the line that runs across the top of the injectors. The fuel assembly on this tractor is a drippy mess. I'm trying to determine where the leaks are.
Once you start disturbing those return line connections, you will chase the leak until you have replaced all the rubber donuts in those compression fittings and bonnet “0”-rings. I recommend looking at a parts diagram and ordering all new seals. There is probably an aftermarket kit available with all the parts that you need.
I had to make my own crow type wrench when I did them once heated the end and bent it to the needed angle to fit in there.
Are Called Eastman Seals, any decent small parts house can get packages of them as generics. May take two small kits to get enough as are same as on my Allis 344 engine.
Sounds like I should leave well enough alone. I believe most of my leaks are around the fuel pump and filters.
Those will also have those type seals on them on low pressure side. And as they age they seep, INCESSANTLY. Only a few bucks a package. https://www.zoro.com/dorman-fuel-in...urn-pipe-seal-kit-904-497-904-497/i/G6861091/ Contains most common sizes, likely to need two kits. Save extras for spares.