Flush mechanism problem

[Steve]

We're having a spot of bother with our bog. Water is trickling into the pan. It doesn't do this every time it's flushed, but what I've noticed is if the flush mechanism cuts off with a thud after flushing, it doesn't trickle. If there's no thud, it does trickle.

Does this valve have any kind of adjustment on it? Or is it time for a new mechanism? The toilet is ideal standard, don't know what model.

If I were to change the mechanism, its this easy enough in these, or is it a cistern off job like the old syphon units used to be?

 

[oldbuffer]

1. Looks like an Ideal Standard SV89067, but check first.
2. As a first step I'd just replace the flush sealing washer at the base. Grip the main (black) part, push down very slightly and turn anti-clockwise. The mechanism should come out to reveal the washer. With the mechanism out, clean and check the area where the washer seats at the base of the cistern.
3. As a second step, replace the whole valve.