Brakes Went Out

[Chris Codd]

My '64 Cadillac DeVille had been sitting for awhile while I was travelling this summer and when I came home it had some issues starting. After replacing the plugs and the ignition coil, it was running better than it had in a long time but the brakes were sticking. I noticed the brake pedal was traveling a little farther than usual when slowing down. Soon after I noticed a hissing noise coming from around the brake pedal. Then I lost the brakes pretty much completely. I couldn't find any leaks from the brake lines or the master cylinder when I took a look around. Is my master cylinder the culprit, or does anybody have any ideas on what to do next? Is it possible I cracked the brake line removing the plugs?

[Chris Codd]

Thank you guys for the replies. I haven't done much more than a quick look around the car as it was late last night when it occurred. I did glance under the dash and look at the neutral safety switch but I didn't see any loose hoses. The hissing noise occurs when the brake is pressed and seems like it's coming from where the brake pedal goes through the firewall. I'll fiddle with the neutral safety switch and see if it makes any changes.  

The brakes were completely redone about ten years ago, so it's probably about time to go through them again. I haven't seen any fluid leaking yet. 

I have not checked the fluid reservoir level or wheel cylinders, but I will go check on them. I forgot to mention, the RPMs go up when the brake pedal is pressed.