I recently went to change out my brake pads, and thought that I'd clean up the brake dust inside the caliper while I had the brake pads out. I gave a squeeze to the front brake to watch the pistons operate, and three seemed to go well, while there was one that seemed to move slower than the other three, it at all. I sprayed more cleaner and tried to clean around the piston which had some grime around it, but it seemed the more I messed with it, the less it moved. I did the cleaning a couple of times, while pressing the pistons back into the caliper each time, to see if I was breaking up any of the gunk. I had the brake fluid resevoir cap off, and of course, fluid was coming out. I went ahead and put it all back together, topped off the brake fluid, and squeezed the brake until I had pressure again. Put it in neutral and the new pads seem to be grabbing as expected. It was the end of the day, so didn't take it out on the road, but rocking back and forth in the garage. I guess my question is in regard to that piston. Is it possible that after I put it all back together again, topped off with fluid, that the pistons don't have to travel all that far with the new pads and don't worry about them? Or should I perhaps look at a rebuild kit and tear it apart if the piston is indeed stuck. Seemed like it was operating just ok when I opened it up, as all pistons were relatively out in equal length. It was only after I began cleaning, losing fluid, and pushing them in that they started going cockeyed. I've got 28K on the bike, and not sure when the last service on the brakes were done, but the pads definitely needed replacing. They were worn a bit uneven on one side. Obviously, just don't want to have any issues. Thoughts? Thanks.