Cars just failed MOT due to brakes being out of balance. the

front N/S is 200 pounds, = Stays steady on the reading at 200
Front O/S is 100, = Goes upto about 230 and then drops back down to 100
Rear N/S 20 and = slowly goes upto about 20
Rear O/S is 100. = stays steady at 100.

I have bleed system and modulators, checked wheel cylinders and calipers looks like the fault is in the braking circuit that does the Front O/S and Rear N/S, the pedal also does drop a bit when u push it. it drops about an inch before it goes hard. anyone had this problem before i think it could be the ABS modulator for that circuit that is playing up.

PLEASE HELP need to try and get fixed for MOT quick.

The cars a F-reg Mk3 Fiesta 1600 s, and has the rubbish mechanical ABS system think its the same as the XR3i used.

Cheers GUYs ur HELP would be appreicated