We rebuilt the front brakes a couple of weeks ago as we were fed up with the intermittent grabbing! 6 pot brakes are awful to set up perfectly, with the self-servo action of the shoes; if they grab, they really do pull.
The problem was it was so intermittent - it would be fine for weeks, then suddenly grab, so you were always on edge when braking.
So, we replaced all 4 cylinders, springs and shoes, and taking advantage of having the backplates off, we re-routed the pipework so the bleed nipple is now on the top cylinder instead of the bottom one.
We're happy now that the brakes are true, and they passed the brake test with almost perfect balance (rears were a little out, but still passed)
Cheers,
Robin.