I'm pretty sure this was an anomaly. I was at the space yesterday
afternoon and had no problem with a 2.5 hour print.
I did clean the nozzles off, as they were caked with burnt ABS. And I
opened up the right extruder and cleaned out the drive gear. It was
caked with ground white ABS. Note: I did not examine or clean the left
extruder, so this might be a task that still needs to be done.
Another thing to note. Someone removed and subsequently lost the 2GB
SD card from that machine, and replaced it with a 256MB. If anyone has
seen this, please chime in. Since John was the one who accidentally
misplaced it, I've asked him to reorder a new 2GB. I'm not sure if the
anomaly was a hiccup caused by a lower speed rating on the SD, but
it's the only thing I can think of. By the description John gave me
yesterday, it's certainly a software hiccup of some sort and not
TL;DR There have been no subsequent print problems with the Makerbot
and a lost SD card is being replaced.