8011 Brakes

Hi all
Just recently my brakes have gone on my old 8011. Just pressed brakes, the pedal shot to the bottom, stayed there (and brakes stuck on) so i rocked her backwards and forwards gently, the brakes came off, the pedal came up but now got no brakes at all!

Any ideas of what to look at first? I don't want to pull her to bits unnessasarily, but looks to me thats whats gonna have to happen.

Cheers

Bruce

you can check on some inspection panel on the rear axle. I'm not sure where these panels are but they are there.