Shutdown wafersaw SNF 2005-05-25 08:06:35: Won't power on

[cbaxter at snf.stanford.edu]

installed y limit back. found z servo motor over current 
and drives to upper limit switch but it won't drive to home
(encoder is bad) eric and i found a spare servo motor on 
the maint. chase cabinet. installed servo motor but drives to
the upper limit and continue driving. we found another 
servo motor behind the tool on the shelved(brand new).
installed calibrated. eric cut two sample dummy wafers with
out a problem..