I had the same problem with mine. I used a Dremel with barrel sanding tubes.
The Dremel spins clockwise. Twirl the barrel sander COUNTERCLOCKWISE
in the hole checking periodically with calipers. Start with a coarse grit.
finish the last .005 to .010 with a fine grit. I fitted mine in about 20
minutes to +.005 and true within .002 TIR.