Quote 小漁 article-

I took out the stick jointe...

usually, it takes a bit of force to get the whole piston out. you will need to use a set of needle nose pliers to pull them out. it helps if you disconnect the lever from the main hose, so that it doesn't create a vacuum.

once you take it out, clean the inside of the lever, and get a lot of grease on the o-ring. you want a thin layer of relatively thick grease, not the liquid lube you use to penetrate.

also, the spring can be a little bit fatigued. you can pull the string out a little bit to increase the tension and your brake will feel snappy. don't do this too much, or the spring will be too strong, and it will be hard to actuate the lever.

you'll need to bleed it again after too:)