Isolation valve leak / weep

[Parcival]

Toilet would not shut off so got plumber round to replace.
Unfortunately the isolation valve started leaking from the slot so he replaced that as well. All good and only took about 15 minutes.

A day later i noticed a small drip that was coming from the bottom of the valve where the supply pipe enters.
Plumber returned and nipped up the nut. Still a small leak / weep.

Plumber returned and remade all the joints and put some putty on the olive.

Still a small weep from same place.

Now we are talking about a very small leek - hardly noticeable.

Plumber is highly competent, have used him for 20 years.

Advice on how to proceed please.

Thanks

 

[denso13]

Hard to say without being there but it should be a simple repair for a plumber. Maybe a damaged olive, who knows.

 

[gas112]

Plastic threads ? Or brass

 

[Parcival]

Copper pipes and brass fittings

 

[oldbuffer]

Might well be olive crushed into pipe. If so will need:
1. The end of the pipe cutting off and an extension adding on. OR
2. If available, a pipe expander to bring the pipe back to 15mm along its length.