OK, so this is a bit of an odd one.
I've got some XTR M975 Disc Brakes, and the right hand (front) brake lever leaks fluid of some description. At first I thought it was a case of having to replace the seals (can you even do that with Shimano brake levers?). However, I went out to the shed tonight to take a couple of pictures of the leaky lever, and it's since occurred to me that there is no reason for brake fluid to be leaking out of that particular point on the lever, as there is no seal there. The area where it is leaking is where the little piston is attached to the lever blade (at the opposite end to where the seal would be), and I can't work out why it's leaking there?
There is a tiny amount of play in the lever blade itself, and when I 'wiggle' the lever I can get the fluid to leak out, as shown in the 2 photos below. The lever blade is a separate entity to the rest of the lever body, and I can't see any signs of leakage around the reservoir seal (at the other end of the piston) or on the piston itself.
The brakes were freshly bled before I bought them, and they don't appear to be feeling any different - the lever doesn't seem to be moving any further than normal when the brakes are applied. I'm confused. Any suggestions?
Before wiggling the lever:
After wiggling the lever:
Note that when I wiggle the lever, I'm NOT applying the brakes, so the little piston isn't moving at all - just the lever blade is.