Perhaps I have been too cryptic.
I have in the past asked engineers about this problem and have had mostly inconclusive replies.
Sometimes they just don't speak english well enough to have a fruitful discussion and that is fine as this is not a country where English is the primary language.
At other times I speak with native english speakers.
The problem occurs on our A332, A343 and A345 types and on almost all flights so I suspect that it is either a design fault or a systemic maintenance system fault. Either way this might explain why the engineers I have asked have not been forthcoming with clear answers.
When I try to probe more I am told that they can't spend the time to bring me diagrams etc as they have multiple aircraft to dispatch and are understaffed. This I believe. I am not permitted to visit the hangar without special clearance and am not going to wade through the red tape required and give up a day off to do that for a problem that is not a safety issue.
This problem has been present for at least 8 years and possibly much longer.
I don't know if it is a problem in other airlines.
I hope that some pprune reader out there might have an insight.
I respectfully ask for information, not further chastisement.