"Jen D" wrote


When the toilet is flushed, water seems to emanate normally around the
bowl rim, the bowl water level rises and then returns to its normal level
but with no particular siphon whoosh, which results in a simple test piece
of toilet tissue remaining in the bowl.

If water is not leaving the bowl as fast as it is entering and the water
level simply rises and slowly subsides, this is likely to be a blockage.
I too have had similar syptoms when a bog cleaner thing got lodged in the
pan waste outlet.
Do you have more than one item discharging into the same drain as the WC?
If so check the rate of flow from other devices compared to the WC just to
get a "feel" for a good flow. Then flush the toilet.
If it's leaving the bowl slowly then you should notice the difference.
I would try one of the spiral wire drain cleaner thingies down the bowl as a
starting point.
IMHO changing the cistern and bowl is most probably not necessary.
I deliberately reconditioned and kept my old cistern, boxed it in and fitted
a new bowl as I didn't want to end up with a pathetic 3/6l flush (I already
have this in another toilet and find it hopelessly inadequate

Phil