Internals on in cistern

[goofy gorilla]

Which way round does the black rubber seal go in cistern valve? One side is flat and the other side as in picture has grooves in it? Also fo I meed to adjust the blue slider on the side of the valve or leave it as it came? Ta

 

[polesapart]

1) Ribbed side to cistern.

2) Probably not, accompanying leaflet will clarirfy.

 

[goofy gorilla]

So you mean as it is put it inside the cistern and tighten from underneath with nut and washer?
Included instructions don't mention anything so I'll leave it as is.