Comment epi2 SNF 2009-11-02 14:34:51: Update rotation problem

[eenriquez at snf.stanford.edu]

Same error "Ch.A rotation step failed homing" but the mode of failure is different.  In the past, the error occured when the rotation motor moved too slowly and doesn't quite make to the home position.  Now, motor rotated too quickly and out of control.  It looks like it has a defective motor encoder.   Ordered a new encoder.  No ETA yet.