B would be the slave cylinder...(piece with flex rubber and pin)
A is the clutch fork extension.
if it is at c then something is wrong definately with your hydraulic line system.
Check the image below
First off check the slave cylinder and see...this could be your initial problem....
Secondly if that is fine, check where the line meets on the top of the box...where the lines connect at the loop with the fastener (B)
Thirdly check the line at the master cylinder connection...... (C)
What is the colour of the fluid.....jet black?....if so then rubbers gone.
If you pur fluid and pump the pedal a bit, and also press and hold down for a few seconds, check to see if any fluid leaked....
if so, then once you haven´t driven the car and it´s cold you may be able so smell the fluid from where it´s leaking.
I still feel you have a problem inside the box, but to be sure, fix the outside problem first...it could save you from having to pull the entire box down