During each Mass, something can go wrong. Because organists play a very complex instrument with a lot of moving parts (even with a digital organ), there are a lot of things that can go wrong. My job, if one of these happens, is to work around it as best I can. Here’s a list of things that can go wrong (not exhaustive) of situations with plenty of badnessitude:
the organ won’t start
This has happened to me, twice. Once was the time linked to in the last sentence, a little more than a year ago. The other was the same organ, about 10 years ago. In the earlier one, the fuse to the organ was blown, so even though the electrics in the church were OK (despite a storm earlier that day), I couldn’t play it and had to go a cappella the entire Mass. This is a grin-and-bear-it sort of thing. If there’s another instrument (such as piano) available, you just go there and report the problem as soon as you can.
the organ shuts off mid-mass (or worse, mid-hymn)
This has happened to me, too. And it was mid-hymn. A momentary power blink hit the church, and the digital organ, as it was (we later found out) designed to do, shut itself off, forcing me to the piano mid-hymn. What we didn’t know was that it had to be reset, so when I went to turn it back on and it wouldn’t go, I had to grin and bear it. Earlier, we had had a close call at the same church before the funeral of the man who gave the land for that church. But that time, the organ (thankfully) turned back on, though it shouldn’t have. So maybe God gave us a break that time, given the importance of the funeral Mass.
there’s a stuck key or stuck pipe
What happens here is either the mechanism is stuck, leaving all the open stops connected to that note playing, or sometimes one pipe is stuck open, so that’s it. If you’re lucky, clearing the system or tapping on the note in question (if you can figure out which one it is) will fix the problem. This happens every so often and usually isn’t a big deal, but when it happens during Mass and you can’t get it unstuck, it can be a big problem.
you have to go to the bathroom, like, really bad
When there’s a choir loft, and the bathroom is in the back of church under the choir loft, this isn’t necessarily a big deal. But if you unknowingly ate the wrong thing or drank way too much water last night, your console’s in front, and you have at least half an hour before Mass is over (and you’re playing for a large chunk of that time), it’s really not much fun. This has happened, especially one time where I couldn’t get a sub and had to play with a 103-degree fever. My throat was just awful (I was diagnosed an hour with a throat infection that, oddly, wasn’t strep), and I had consumed a lot of water, and you can guess why I needed to bolt out of church in a hurry in front of everyone. Not fun.
there’s some sort of disturbance during a hymn
Thankfully, this hasn’t happened to me yet. And that’s a miracle, as really, this is a vague category. Anything from a major medical emergency to a wacko charging the altar could happen, and really, I don’t know what I would do. Would I stop mid-hymn, right away? Look for a stopping point? I have no idea, and I fear I won’t be able to figure out how I deal with this until it happens.