Check your copper washers for deformities from being installed incorrectly. Generally they can be problematic when trying to get multiple uses out of them. I do not know what the torque specs are for those banjo bolts are. I tighten them as tight as I can with a 3/8" drive ratchet wrench. I am not a gorilla, BTW. If they leak after that, I will go will a 1/2" drive ratchet and go a little tighter.
I avoid starting the process with the 1/2" drive ratchet because you can snap a bolt or bugger up the treads if you aren't careful.
Admittedly, this is shade tree technique, but I hate working in the sun.
Carl
