Nobody has really said why they needed maintenance. Just that they were doing maintenance on them in preparation for the Super Bowl. Being maintenance, I assume it was to make sure they properly functioned during the Super Bowl, not a situation where stuff was stuck in them and they needed to be repaired. But, I don't really know.
It's been awhile since I looked at them, and I never really took a very close look obviously, but my recollection is that there isn't much of a gap where stuff could fall in and get stuck.