clutch master and slave cylinders

[grimmy]

Right guys I know the sheddist kit is the way to go but they tend to be way to expensive for me.so my question is.what makes the o.e ones fai?l I know the brackets are rubbish and the freelander ones are a decent replacement if needed but the actual slave and mast.er do they actually completely fail spewing the fluid out everywhere or does the fluid "go off" causing the arm not to push the clutch arm in far enough so therefore can the fluid be replaced to freshen it up a bit.I know they are a bitch to bleed but it is possible.just kinda blue sky thinking here as I have a bit of a notchy gear change and the slave is obviously my first port of call so anybody else got any thoughts on this?