The last couple times I went flying there was oil under the calipers on the floor. This was an issue 3 years ago at annual. We removed the calipers and took out the pistons to clean them up. There was a lot of corrosion inside the caliper where the piston goes. We cleaned it up really good with scotchbrite and put a new seal kit in it hoping for a good outcome. Well I got 3 years out of that but don't think it will work again. So now I'm on the hunt for 2 calipers in great shape.
The IPC says this should be part # 061-01900