Help needed! Fluidmaster 400 + blue flusher bit won't flush!

[garrrrrr]

Hi, some help needed please.

Toilet was flushing fine yesterday, but suddenly stopped.
It fills up ok, but when the flusher handle is pushed down it literally trickle flushes!
When I manually push on the blue tube (pictured), it is just very very slow to flush the water out (a slight vibration as the water flushes out) - the water is coming out too slow to flush away the toilet.
I have tried putting my hand to the bottom of the cistern and manually lifted the blue bit (I think it was the blue bit) up to let the water flush, but once again the water comes out very slowly into the toilet.

It fills up ok, just won't flush!

Any help appreciated.

 

[garrrrrr]

Bump

 

[seco services]

have you tried taking it apart ?

 

[kevplumb]

urgh i wouldn't go in there it's mucky