>>After many months of diddling with a score - you know, moving things all over the place, changing keys etc. - I find that some of my notation is without the proper accidentals<<When changing keys, you have a few options. You may have selected an incorrect option.
My best guess here is yes, you must go through it. Sometimes it is better to just do it and get it over in a short amount of time rather than spend days looking for an instant fix.
What I always do is back up before diddling, and then "save as" before tampering with a score. Go the the "save as" file and diddle. If the diddling works out, then replace the file. But ALWAYS have a backup and/or original score!!!!
Good luck, and have fun composing.
Robert
