Toilet flushes constantly

[alisonjb]

Our toilet has started to not stop flushing. After a full flush, instead of the cistern just refilling and stopping, once the main flush is over and the cistern has filled a small trickle of water continues to flow into the pan accompanied by a noise from the cistern that sounds like it's still filling (similar in volume to the end, rather than the beginning of the flush cycle). Can someone advise what is wrong and what I need to do to fix it myself please (and also whether the job is difficult/requires specialist tools)? Thanks.

[stoneyboy]

alisonjb,
There's a good chance that the cistern is overfilling and the excess water is overflowing through the siphon/flush unit. Lift the lid and adjust the ball valve so the full water level is lower.
end

[alisonjb]

Thanks stoneyboy - tried this, but unfortunately it didn't work. Ended up replacing the valve and then the ciphon, but it works now! Alison