What was found
ON ROLL OUT AFTER LANDING, AFTER ENGAGING MANUAL BRAKING, ALLOWED AUTO BRAKES LO TO SLOW ACFT TO 60 KTS. BRAKES STARTED SLIPPING AT APPROX 48 KTS GND SPEED DOWN TO ABOUT 15 KTS GND SPEED. R & R SELECTOR VLV ALT BRAKE IAW AMM 32-42-11*-PB 40. OPERATIONS CHECKED NORMAL, NO LEAK NOTED. R & R LT NR 1 & LT 2 TACH GENERATOR IAW AMM 32-42-57-PB401. PERFORMED FUNCTIONAL TEST OF TACHOMETERS IAW AMM 32-42-00-720, TEST FAILED. SEE LOG PAGE 635464 FOR FUNCTIONAL CHECK, PN & SN C20105000-2, 51573 & 51577. FUNCTIONAL TEST REQUIRED FOR TACH GENERATORS NR 1 & NR 2, REF L/P 635463. DUE TO FAILED CHECK, PERFORMED FUNCTIONAL TEST OF TACH GENERATORS 1 & 2 IAW AMM 32-42-00-720. FUNCTIONAL CHECKED GOOD.