I've contacted Hope so often about C2's[inc levers etc] to the point they phoned me at home and told me to drop it.
Best really buying sets or if you can find them ,parts.Keeps things running.
I feel i must point out that although they are some of the best brakes ever made they will wear out very quickly if you dont know how to look after them.
One of the biggest problems is damage to the sides of the piston,this happens because as the pad wears and you dial it closer it leaves the piston sides exposed to the elements.If you do not wash the crap from them after each ride they will start to become pitted and start dragging grit down into the seal seating, scoring the inside of the calliper.This will lead to the calliper leaking around the sides of the piston.
Pistons or inside surfaces also need to be slippery smooth or the piston wont return and no amount of new seals or services will sort that problem
I went through about 8 complete sets trying to find a set that matched the condition of the ones i stupidly sold.
I have them now[going on the Santa Cruz project] and they're not ever leaving me
1976 Raleigh Chipper,1991 Muddy Fox Adventurer, 1992 Raleigh Diablo ,1992 Rudy Project, 1995 Cannondale M200 ,1997 Santa Cruz Tazmon ,1997 Specialized Stumpjumper ,1997 Specialized Rockhopper ,1997 Marin Quake 9.0,1998 Marin Pallisade trail ,1998 Raleigh Torus,1999 Orange Clockwork , 2005 Kona Hahanna , 2010 Orange Pure7
The Marvellous Mechanical Hope Collection