What was found
35 MINUTES INTO FLIGHT AT FL 340 LEVEL 1 HYD 1 OFF. HYD 1 QTY 2.6 GALLONS. ONCE SLATS, FLAPS EXTENDED QTY IN HYD 1 DECREASED TO .2 GALLONS WITH LEVEL 2 HYD 1 FAIL ALERT. FOUND NR 1 BRAKE SYS PRESS TRANSMITTER T2-66 LEAKING. R & R NR 1 BRAKE PRESS TRANSMITTER IAW AMM 32-47-01-2 THROUGH PAR 3 B STEP 7 WHICH INCLUDES PRESSURIZING & LEAK CHECK, NO LEAKS FOUND. ALSO CHECKED RT & CTR WW & FOUND NO FURTHER HYD LEAKS. SERVICED NR 1 HYD SYS & CLEANED AREA. NEED TO CONTINUE WITH STEP 8 THRU 10 WHICH INCLUDES BLEEDING THE DUAL BRAKE CONTROL VLV. NR 1 RESERVOIR HAD 2.6 GALLONS QTY AT BLOCK IN. COMPLIED WITH BLEEDING OF DUAL BRAKE CONTROL VLV IAW AMM 32-44-04-2. ACFT OK TO CONTINUE.