front brake issue

i just pulled my wheels and tires off for the first time in a while to change the front brakes on my '99 fourtrax 300 4x4. the pads are worn bad but also the pistons (i dont know the proper name for them) that push the pads out and all of the hardware surrounding them are rusted pretty bad. also, when i pull the brake lever only one of the pistons on each side functions. the other two just dont move. is there anything i can do to salvage the brakes on the bike now (besides getting new pads, im gonna do that anyway). I dont want to have to buy the whole front brake assembly if i can get by without it. thanks for the help.