I too had similar issues and thanks to everyone esp the frequent contributors! I took slave cylinder off, inspected, pushed it in all the way and quickly fastened it to sprocket cover and casing. Then ordered parts for slave cylneebuild and some new lines. Just turned 50k!
If you are doing the slave, may as well do the master at the same time. Its easy to do and will have similar age of seal inside it, so its probably due for a change. Then you only have to bleed it once. A tip for bleeding after a slave re-build. Push the slave piston all the way back inwards with a C clamp, hold it there and bleed it. Do this before bolting it back onto the bike. With the piston back there are no areas where air can still sit in the bore. Being all the way back will make fitting it to the housing much easier too. You will then need to pump the master a couple of times to push out the slave, so don't forget to top it up afterwards.