Could you have a look at this thing in the meantime, now that it's clear since some weeks, that in "Galaxian DX" this problem with the Autofire don't occure? Then this could be fixed in Galaga too, like you mentioned.
And one question more. Somewhere here in the entries you wrote, that, when less colors would be used for the attacking enemies, technically more possibilities would be there, for improving other things to make Galaga, which is already good, even more closer to the Arcade version. And you also wrote, that you decided against it, because you wanted the sprites to have more colors. Just one question to this - how about a second version and then a selection-function for the player, in the beginning of the game, where he could choose, which version of the game he wanted to play. And then a second version would be created, with a similar look, when it comes to the colors, than for example the game "Tiny Galaga", that came out last year for the Amiga? Only two colors, but nevertheless, it looks and plays really good. Looks like a LCD game on older game&watch handhelds, when it comes to the colors. Everything could be the same like now in your C64 Galaga, just with less colors (two or three) but therefore with some improved other things? What do you think? Player then could choose everytime in the game-menue, which version to play and this version then reloads.