He is not making it up.
Take a screw/bolt and put a large nut on it. On the nut you have a cone shaped cap that pushes against the inside of the piston, applying ebrake. Three things happen to these pistons, that make it where they have to be replaced. You can rebuild the caliper, but you have to replace piston.
First, piston center button area leaking. This is internal to the piston.
Second, Cone assembly is not returning to rest position.
Then, Nut stuck on cone.
The cone and nut make up a racket assembly. When it comes out of adjustment the cone allows the nut to get another click on the bolt. the next application has to make the cone contact the inside/back of the piston or the racket just clicks back. When installing new pads, if the Hydralic part of the piston is applied before setting the Ebrake section the, the cone never touches the piston. The piston would have to be pushed back against the cone, with some tension against the piston, then using the lever on the caliper you can adjust the piston to the pad. If the pad wears down enough before the piston has a chance to, bump it up a notch, it won't adjust further.
You would have to back the piston against the cone again. That's just to keep it adjusted if extended too far.
Now you take into account the crude it has seen and the last time the guts of it have seen light, most likely you need one.
Disconnect the cables at the adjusting flange. If you want you can remove them from the caliper if you want but not really needed to check. Use something to grab each caliper cable and make sure the levers pull and return. By hand you should be able to apply the hand brake and pull the main/center cable back down.
I put a pair of needle nose vise grips to make the next easier. Move the cable levers as far to stop as you can. If the lever stops half way or less and the piston is against the pad it is adjusted.
If the lever goes almost to the end. Try applying the lever by hand to get it to move out. May have to do it quick to get the racket to move. If it still won't adjust(bad piston) Sticking nut
And if the lever goes all the way to stop. place something between the piston and the pad to move the piston back against the cone.
Again by hand, apply the lever to attempt to adjust. If not (bad piston) Sticking cone.
[This message has been edited by cmechmann (edited 08-12-2013).]