> My BA123 needs new castors too.  I find the two back
> casters are easy to
> purchase -- they are the "plate 01" style with the 1
> 1/2" square plate.
> 
> I cannot find replacements for the two front casters
> -- they are the
> "plate 13" style with the 1 3/16" x 2" plate.

Hmm, I had the exact opposite problem. I found the
rectangular plate ones easily at the local Lowe's
(U.S. chain of home improvement warehouse stores), but
not the square plate ones.

-Ian