You do not need to go to Antal or Harken for bearings. These guys do not make the bearings they use in their blocks, they just buy them from a bearing manufacturer. And then resell them to you for a 300% markup. Just take your sheaves and go to a bearing supply company, they can get you replacements
for a fraction of the cost. Or you can measure the bearings and order replacements
from McMaster Carr, a great company, if you are in the US you will order them one day and have them delivered the next.