Before loosening anything why not try to seal it in place. I have successfully done this and it has held for three years. Mine was on a Mitsu TD04 but the concept is the same.

Remove the oil and crud from the return line and the block. Use a small screwdriver, dental pick, whatever, to remove all crud and buildup from the groove between the line and the block-all of it.

Use lacquer thinner to completely remove any oil residue from the surfaces of the block and return line and especially the groove between them. QTips, rag on a stick, anything to get every last bit of oil and dirt.

I use a silicone caulk that I get at Lowes. It comes in a large tube with a removable tip so you can store it with the plug in the end. Simply pull the cured silicone from the tip when you want to use it again.

Build up the silicone around the return tube. Start by forcing it down into the groove with your finger to fill the space entirely all the way around, not allowing any air space to remain.

Continue adding silicone as though you were "welding" with it. Bring it out onto the block all the way around as well as on the return line. It should be heaviest in the area that will reinforce the groove.

Most important is to let the silicone set up completely. Minimum of 24 hours, but the longer the better.

I was under my car the other day and it is still free of any signs of leaking again. Good luck.

Randy