front master cylinder leak 71 ford f250
 

Hi, I changed out the old brake booster but kept the master cylinder. I'm not sure if I should have replaced the master cylinder too. I'm not very experienced with mechanics but this was about a year ago, I bled the brakes afterward. My problem is that the front resevoir of the master cylinder was empty when I checked it this spring. I filled it up and now fluid leaks out of that cylinder still. I suppose I need to bleed it again but wonder why it leaked out in the first place. Maybe asking a question best answered by myself but, thanks

I forgot to say, it leaks out of the lid, or cap. only from the front cylinder though. I cleaned the lid gasket off thoroughly. I assume I should have re-bled the front brakes after I noticed the cylinder was empty, but don't know why it went empty in the first place.