Personally I think the Root cause of the failures is the release arm within the gearbox, this starts to freeze up and put extra load on the hydraulics, causing them to break at the weakest point, which usually is either the bracket or the plastics of the slave itself!
Officially they are non-bleedable sealed units, unofficially I have bled loads
"Notchy" gear change can also be the gear linkage being worn, either upgrade the components and re-drill the pins or use a ZR (or Ford Ka IIRC) Steering column universal joint and replace the whole gear linkage UJ... - Note, in one or two cases, the pin has started to fall out and by knocking it back in it resolved the notchyness...
Worth looking at that too!