Tim, if they're out of balance try some repeated hard braking. My MOT tester told me to do this and each time the balance improved until it was within specs for a pass. He said the brakes need to be used quite hard or the pistons don't travel much and corrosion can affect them, more so on vehicles not used often.
Peggy can do 78mph!
If I told you I was a pathological liar, would you believe me?