Legacy .plx (PlexonIO) read error

[MisterVulcan]

I'm using an old version of Plexon's Offline Sorter (2.8.8) and Sorting Client (1.21) software which saves with the old .plx format. Python-neo version 0.4.1. Below is the typical use case.

In [31]: reader = PlexonIO(filename='03-07_1650.plx')

In [32]: blks = reader.read(cascade=True, lazy=False)
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-32-1dd5e1af6904> in <module>()
----> 1 blks = reader.read(cascade=True, lazy=False)

/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/neo/io/baseio.pyc in read(self, lazy, cascade, **kargs)
    119             if not cascade:
    120                 return bl
--> 121             seg = self.read_segment(lazy=lazy, cascade=cascade,  **kargs)
    122             bl.segments.append(seg)
    123             bl.create_many_to_one_relationship()

/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/neo/io/plexonio.py in read_segment(self, lazy, cascade, load_spike_waveform)
    161
    162             if dataBlockHeader['Type'] == 1:
--> 163                 nb_spikes[chan,unit] +=1
    164                 wf_sizes[chan,unit,:] = [n1,n2]
    165                 fid.seek(n1*n2*2,1)

IndexError: index 1 is out of bounds for axis 1 with size 1

Note that this sort of used to work with an earlier version of neo, and only when I was working through the OpenElectrography interface and not a python prompt. Now it's just broke. Any tips?