I am a new owner of a 2012 Wee. Lovely bike but I have a problem and I'm seeking advice on what to do next. Yesterday the rear brake suddenly seized i.e. pushing the brake pedal did not operate the brake. Upon examination the pedal can move but cannot push the piston in the master cylinder. I cracked the union on top of the m/c and fluid appeared so the m/c itself is okay. I can lever the pads away from the disc so they are not seized. There appears to be something preventing the fluid moving beyond the m/c. The bike is still useable and the abs light goes out as normal. Any ideas?