Analogue-sequencer

I adopted the early P3 formerly played by John Duval.  Shortly after 
it arrived, I upgraded the bootloader and then up to firmware 
3.1.005 with no problems.

Time goes by; the instrument is great.  I decided ti was time to 
upgrade to 3.1.006 tonight.  I used the sys file from sequentix.com 
with MidiOx through an M-Box 2 into the P3.  This is what worked for 
me previously.  FUNC + PAGE at power up, F3 to accept f/w, then send 
on the sysex from MidiOx through USB to MBox2 and MIDI cables to P3.

BAD DATA appears almost immediately in the window.  The firmware 
does not updgrade.  Now when I turn on the P3 I get CHK FAIL = 
9C43.  I select F3 and try again.  I check MidiOx for buffer and 
milliseconds pause after F7.  No dice.  I pull out ym old MidiSport 
USB 4x4; no difference.

Any obvious issues or solutions here?  I am very inexperienced with 
Midi in general.

I have not changed PCs, drivers, OS, firewalls or anything since the 
last successful upgrade.

Thanks in advance,
Jim W.
San Mateo, CA