My brake have been feeling spongy and soft so i checked out my master cylinder to check the fluid, and the front smaller compartment is empty. im going to fill it up today when i swing by autozone for some fluid. but what are the 2 compartments for? why is the front one empty? could there be a leak and have one empty and have the other still work? my brake have been progressivly getting worse, faster then pads wear. Thanks, you guys are always a help.