V11S Rear brake master cylinder failure

I was bleeding the rear brakes on my V11TT because they were starting to go soft. Then I discovered that the rear brake wouldn't even bleed
and was bubbling at the shaft seals. Definitely bad with only 12,000 mile on the bike. I yanked the one off of my Sport 1100i (which isn't
in running mode at the moment) and put that on the V11TT. What I found though, was kind of disturbing. The rubber cover for the stoplight switch was completely full of rusty water! I suspect that water eventually migrated into the rear brake cylinder causing it to fail. Or not. Either way, if you're going to ride in the wet, or wash your bike a lot, it would probably serve you well to pack these covers with silicon grease or something.

This photo shows the assembly after cleaning.

Carl Allison
Modesto, California