I tend to doubt that the leak is coming from the wires or unit itself because it is incased with epoxy about 2 inches plus worth, unless its cracked.. doubt that one also. My bet would be the nut is cracked and that is ALL that's needed. The think the fuel is trailing from the seal down the wires. Pretty hard to distinguish that one clearly while in place.
If he has a stock of nuts I’d say put one on and we’ll keep an eye on it… I see no reason you’d need to wait more then a hour for the job. If he is familiar with this problem and has really looked at how the part is made, I think his opinion would change.
Good luck man.
edit: added pictures to show how the nut cracks.