It seems to me that this wide Y is due to fluctuations in the beam position, not due to a large beam size. The plot just looks at BPM values. The script chart of the Y BPM positions (http://www.jlab.org/~adaq/halog/html/1011_archive/101112030403.html) shows this too.
I don't see any obvious reasons why MCC cannot lock the beam positions, as before. We don't want to lose a lot of beamtime, but maybe this problem should be discussed in the 8AM meeting if not solved by then.