good am mga sir! have this nissan eccs supersaloon 93 mdl. pinatingnan ko sa mechanic kc mahina yung brakes and tumitigas yung pedal brake, na bleed nila para mawala yung hangin and replaced the caliper kits, pero ganun pa rin, medyo me hangin somewhere daw and they advised me to replace the servo (rpm) kc mukhang doon nagmumula yung singaw.they also found out that the speed (rpm)is not anymore stable and nagbabago minsan namamatay and bumabagsak yung rpm. my questions
1.the servo has something to do with the brake problems?
2. if i'm going to replace it, saan kaya makakakuha ng surplus and how much? medyo mahal kc bago umaabot 18k.

salamt po.