Jeff's 727 rebuild thread
Is the notch in the lug narrower on the new band? If so, it might not be seating all the way onto the anchor link cross bar even though it feels bottomed. Could the cross bar on the anchor, or the anchor link itself be slightly tweaked so the notch wont seat squarely? Maybe give the anchor link end of the band a good whack with a hammer and long screwdriver to make sure it's good and seated.