I have 2 seth thomas adamantine mantle clocks. One is a humpback (89 movement), the other is a "napolean hat"? (89AL) - Can anyone tell me what the difference in these movements are? I know I'll probably be shot for saying this, but the 89AL movement is in poor shape, 2 broken mainsprings, broken teeth everywhere, a pretzel for a hammer arm, etc. but the case is great, and the humpback case isn't so great but the movement is ok, (keeps great time but doesn't strike.) I'm thinking about swapping the movements, depending on what the difference is between the two. I can't repair clocks, but I'm thinking the 89 would be an easy repair, where the 89AL would be a total overhaul.