I also decide to get some new bearings for the blocks because the backlash on the China bearings was serious. I fitted a shim between the outer races but with the locknut fitted there was still slight play, the shim was the thickness of a Guinness can which in this application is thick. I also took a skim off the block to make sure the outer races were being clamped.
I think I remember Dean saying some time ago that the tubular spacers on the BK bearings are not always long enough and that he had made fresh ones. It is there to enable the lock nut to push the inner races together.
I might be talking crap though ..Clive