Overflow Pipe From Downstairs Toilet has Constant Drip!

[Neilx5]

Good afternoon all,

My overflow pipe from the downstairs toilet has a constant drip and I hope you can help.

As you can see from the images the water level is nowhere near the top of the overflow pipe. There is an occasional small drip from the blue nut to the right but nothing to force the water down the pipe.

When the water is stopped the drip stops, but for the life of me I can’t see how it’s dripping when it’s not going down the pipe!

Regards

Neil