Brake failure?

Originally Posted by monkey

Must be a leak so slight it doesn't let fluid out but air in.

could be, to feel the difference after just 2-3 laps it would have to be many small leaks. A light brainstorm while painting woodenmouldings in our hall gave me some more ideas: maybe there is a small suction action going on inside the mc either when pumping or on return, so when hydrostatic pressure is equall there is no leak, but if there is "under" pressure it sucks in air if there was a hole/weak area somewhere. Could well be there was something wrong in the rubber form process for just that part and that it ended up "raw" or poorer quality than it should, maybe the guy should have sent it away to have it tested, but he just fixed it so he could go have fun again the following week.