As for the rust I'd go with PB blaster or some of this stuff called Kroil "the oil that creeps", I use it to clean and lube my rifles but it works awsome on little rusty bugger bolts n' such. For the cir-clip I got a pair of the cir-clip pliars from harbor freight, realy cheap crappy ones but ground down the points really skinny and then they will slip between the piston and the wall of the master cyl. no problem! try it!