That line about your level being "off just enough to throw the whole setup out of whack" hits home. Had a buddy go through almost the same thing last summer on a school job, he swore it was the chart or the angle sensor and spent a whole morning on the phone with the dealer. Finally the foreman walked over, pulled his level out of the case, and the bubble was sitting a hair off center. Thing had been bounced around in the truck bed for weeks and nobody ever checked it. After that he started zeroing it out every morning before the first pick, takes ten seconds and saves you a day of chasing ghosts.

Wait, a single balloon popping was part of it? That seems so small compared to 20 kids screaming but somehow it's the last straw that tips everything over. My brain just can't wrap around how one sharp sound on top of all the talking and singing would be the thing that breaks it.