Overflowing toilet- how to fix fill valve

Hi all,

If anyone can help with me diagnose the issue with my overflowing toilet I'd be massively grateful.

Cistern is constantly leaking. Overflow pipe is constantly filling up and based on my youtube trawl I believe the fill valve in the issue. However, I can't see one similar to mine online so don't know how to move the float on the stem? Have I diagnosed the issue all wrong?!

Many thanks

It looks like one of these. Also how to fix
View attachment 1588890585706.png
View: https://www.youtube.com/watch?v=rH7pIeFR_ac&feature=emb_rel_end

If it is the flomasta one. You can't adjust the float level you adjust the stem height via a grey tab on the stem. Might give you a better look in if the pop the Syphon out twist it 10 degrees whilst holding on to base. Obviously turn the water off before you try adjusting stem height or it might bounce off the ceiling whilst you are getting wet

Hey, just a handy info for people like me who will potentially end up here in the future. There is also a YouTube video about how to fix leaking of this particular valve by simply replacing the white, o-ring seal at the bottom of the unit. However, I did take it apart and found out that the white ring was not the root cause of my leaking. Actually, the white seal is very robust and will not likely cause issues. My leaking was eventually caused by another smaller black o-ring which was located under the top cover of the grey handle. Over time limestone had developed on the top of the ring making the valve unable to close properly so water was leaking through the overflow pipe. It took 1 hour to learn and find it out with zero experience but once you understand the mechanics, it is a 5-minute fix without the need of either removing the pipe or buying and waiting for a new unit for £8. You simply need to gently remove the top grey part with a screwdriver, take the ring out and clean it properly.