Yesterday I intended to upvote an answer, but accidentally downvoted. I did not notice this and did not change it within the five-minute window for changing votes. Later that day I noticed a drop on 1 in rep and discovered the accident.
I could not change my vote. But since I have editing priveleges, I edited the answer trivially (inserting 3 spaces in its source text) and then I was able to change my vote.
I don't really understand the reason to lock in votes after a certain amount of time in the first place, but I have read that it is to prevent some kind of gaming of the system. If the idea is really to prevent gaming of the system, then I guess I should not be allowed to game the system with my trivial edit either.
Or maybe editing rights should come with the right to change one's votes?