brake pulling to the right side

[Ahu]

Hi 2WD Nissan D21 1992 has a brake issue... when brakes are applied it pulls the vehicle to the right, it turns the steering wheel to the right, pulls to the right quite sharply.. to keep the vehicle straight i have to turn to left when brakes are applied.. i have installed new brake pads, the front disks have been equally polished recently, ball joints..etc has been installed, wheel alignment has been done, the mechanic said the brake fluids flowing equally to the wheels ( i am not sure how far that is true) what may be causing this issue ? any good mechanical garages to fix this problem in Colombo area ? ((( this is not the case always sometimes it runs perfectly all of a sudden it turns the vehicle to the right, sometimes it turns slightly but at times it turns sharply,,)

[MV-5]

my guess is , there is issue in the front left brake. probably front left brake caliper piston movement might be obstructed due to some mechanical error (in the piston or cylinder or its shape ).

as a result of this , brake will be only applied to front right , so front left wheel is to free to rotate which cause to turn the vehicle to right side.