i had this prob with some tektro aurigas and avid juicy 5s. i got some silicone grease and pumped the brake lever so the pistons were nearly out of the caliper and put a generous amount on the sides of the pistons (wiping off excess). then work the pistons back in and out a few times and bleed them, and hey presto no more sticky pistons
dont stop here!, this is bat country.
current rides: 2004 kona cindercone, 2003 kona stinky and a saracen xcell also a fire eye flame all mountain work in progress