MOT fail on brake balance

It's amazing how much imbalance you need before a car will start to pull noticeably.

Your problem can often be cured by pumping the piston out/winding it back in a few times while spraying copious amounts of silicone oil onto it.

Yes or no, depending on which end is out of balance.

The rear end will take much more out of balance than the front before you feel it, mostly because it's the steering end. The rear is the most usual end to be out of balance because cylinders are far more prone to leaking than calipers. The rear will also put the parking brake out of balance. If it's only the parking brake out of balance, then just a new cable and/or freeing off the pivots on the linkage should sort it.

HTH Steve

The car has disks all round, but it was the fronts that are out apparently.