Frustrating toilet flush pipe leak - any tips and tricks?

Warning: amateur plumber at work...
I installed a bathroom suite five years ago, and until a month ago it worked perfectly. Then I got a leak from the toilet soil pipe outlet. It turned out to be a split connector, which I have replaced.
Unfortunately, having now taken the toilet bowl out a couple of times to fix the original problem, I now have a leak from the connector to the bottom of the cistern - where the flush pipe exits.
I have tried packing with petroleum jelly; I have tried winding PTFE tape around the outside of the thread; I have replaced the O ring. I still have a miniscule leak - about 3-4 drops in an hour after flushing. I fear that the thread on the outlet might be crossed as a result of overtightening.
I seem to have a few options - please could you comment on these?
1. ignore the leak - it is only a few drips per flush. It probably doesn't matter. (I'm not too happy with this one myself)
2. pack around the *outside* of the connector with plumber's mait. (Might work, doesn't seem too sensible)
3. put silicone gel into the connector, and hope that it seals off the leak. (Might be a problem to remove later)
4. replace the flushing mechanism in the cistern, and install a new connector to replace the possibly crossed thread. (relatively expensive, but might have to be done finally to correct the problem).
I should mention that I am likely to be selling the house in a year or so (market permitting), so I could live with a minor bodge - if it works!
Thanks for any suggestions,
John.
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Could it be a leak between the siphon and the threaded extension. I think there are rubber washers each side. The one inside is the most important.
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It could be - it is hard to tell for sure (the cistern is enclosed in a box assembly, which is a pain to get into, without removing the whole toilet bowl etc).
John
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"John E" wrote

If your cistern is the "traditional" type, then the leak is most likely to be from one of two places: 1. The syphon or flush unit is not sealing against the base of the cistern (internally). This is quite likely from the raving around it has experienced, but would be constant rather than appearing only at flush time. The water leaks down the syphon threads below the cistern and appears on the connecting nut for the flush pipe. 2. The tapered rubber washer is not sealing between the syphon discharge and the flush pipe.
Recommend you get a new flush-pipe-to-syphon sealing rubber and some plumber's mait. Remove the syphon which will allow replacement of the rubber seal to the bottom flush pipe. Re-fit syphon with ring of plumber's mait around under the base to seal, introducing new flush pipe sealing rubber as you do.
Phil
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John E wrote:

LSX around the washer inside & the nut outside.

Not really expensive - about 8 in Wickes for a siphon.

--
Dave
The Medway Handyman
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Thanks to all who replied.
John.
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