I had a leak that was internal to the caravan and changed the seals to no avail. I ended up replacing the socket yes a bonded in one! Took a while with a thin scraper to gently prise it free, new one is screwed in place, with sealant so this would also need prising off if it comes to it.
but one thing I noted was the internal push fit connection had to be pushed down against the flex of the pipe to re-attach it so maybe over time this was distorting the socket enough to cause it to weep?? A bit of replumbing and the connection is now straight. (And so far leak free).