It's a 2005 lever, do u have a water bleed ? What has happened is that the water bleed has caused the nylon piston to swell up and as you have pulled it has pushed it and now got the piston stuck, the way to solve this is disconnect the hosing and take of the lever blade, then with the grub screw still in, get a track pump and where you would put the hosing put he pump in there and pump and this should cause a pop noise and the piston will come out and also the spring, you can either then leave the piston some where to dry to unswell it or you could sand it down a little, or you could buy a racing line piston which do not swell up and are fine to bleed with water