There's not much in there, Loki.  It's a good bet there's just a chunk of debris lodged somewhere from a worn-out main seal.  That main seal is a simple 3/4" rubber cup that any decent auto parts store should have.  If there's no fluid dripping out the back into the foot well, then the back-up seal is still good.  I'd try just disassembling everything, cleaning all the parts well with alcohol, and re-assembling with a new main seal and some good Lockheed brake seal lubricant (it's a red grease usually found in little aluminum foil packets).

Good luck!

-Dave G.