Has the same problem with my MC16. I took the caliper apart, removed the pistons and found a lot of muck under the seals. Took the seals out, cleaned the muck out, used some wet and dry on the the pistons to clean them up and then put the old seals back in and used syntheitc lubricant on the pistons before I pushed them back into the caliper.

Put it all back together, and after filling with new brake fluid the brakes are working like new.