Shower mixer pull up not working anymore

[omph]

Got one of these a few years ago:

https://www.amazon.de/-/en/GROHE-Eurosmart-Mounted-Shower-Mixer/dp/B00505EKVK

The pull up for the shower has stopped working. It'll go up but water only dribbles. Anyone know of possible reasons it may no longer work ?
I have taken the pull up bit off and cleaned out any limescale but the buttom bit where the water comes out is round and has no place to put a wrench.

 

[oldbuffer]

1. Have a look at https://www.grohe.co.uk/en_gb/eurosmart-single-lever-bath-shower-mixer-1-2-33303003.html
2. Might give you some ideas on how to remove and check.
3. Are you sure the lower part of item 5 is completely round. Very often they have flat on them to enable them to be removed.

 

[Justin Passing]

It may have part 6, a non return valve shoved up its bottom. They can go wrong/swell up. I've broken a couple up and "forgotten" to replace them.

 

[omph]

Thanks for the help guys. After looking at the schema and dismantling it was a simple case of reseating the o-ring and it's functioning as normal.