Ballscrew Slop Question

Hello All, I just installed ballscrews on my Bridgeport mill, in
preparation for a CNC conversion. They were purchased from Hi-Win
Industries. After installation, I noticed that there is about .002-
.003 slop in either direction on the X axis. (the Y seems OK) I have
been told that my bearings that are in the left side end cap might be
at fault. Could this be true? Since the original Bridgeport didn't
need to have zero backlash, are they even thrust bearings at all? If
I need them, does anyone know of a cheap source?, the ones I checked
for the bridgeport(20mm id x 47mm od )are $270.00 for two!!! Or does
anyone know of a different solution? Thanks in advance; John