The brake valve (doseur) is a pig to get at - and is often blamed when there is in fact nothing wrong with it.
Easiest way to change is is to get a left hand drive car - when its over the gearbox.
hydraulic woes continue
Well just back from mot centre and all bad she failed on headlight alignment (which i kind of guessed ) rear brake inbalance, a hole in the offside sill which i had not seen, lhm on the offside rear wheel ,which i think is a bit mean and the best of all spare wheel carrier loose... why because there is no spare wheel in it!! and then to cap it all the suspension would not go up to get her off the ramp so not a good day methinks that there could well be a meteor on the drive quite soon