I am in the process of cleaning up the front callipers on my MC21, incidentally the forks and calipers are MC28SE.

I am always cautious about what I use as a cleaner around the seals etc and stay away from brake cleaner if I can.
I had heard a tip about good old washing powder, the nasty stuff not the eco stuff...so I tried it out on the lines to see what might happen.

I made a paste out of it and applied a little to the left hose to see what the effect was...I left it on for about 2 minutes.