Brake booster woes

[Hogtrough]

Yesterday I took my '63 around the block and the brakes were alarmingly bad, all the effort I could muster would barely stop the car (it has a Turner front disc kit with a dual master added earlier this year). I assumed I needed a new booster, but now am not so sure. The pedal sinks as normal when starting the car and it feels like it's getting vacuum, but not enough. Was wondering if anyone knows where this hose leads, as I'm thinking it may be the source of a leak. Maybe the dash vacuum gauge?   Everything in the engine compartment looks OK. Anyone ever had a booster that went out, but not completely? I was under the impression it was all or nothing. 

Edited 3 hours ago by Hogtrough

[Hogtrough]

Got lucky , it was just this hose leaking air. Disconnected, plugged the port, now stops on a dime again