hahhaa, Beer bottles hit that video game top lots harder than that hammer did. It's pretty thick glass. I wasn't actually tapping on the glass itself. It's my Scramble game, which I also bought a Super Cobra board that I can change out when I want.
To change the music, I have to open them, and grind out 2 rivets that hold the old movement in to place. I can use those same holes to put the screws in from new movements to re-attach the new music.
I can only get 18 note (or even 12's sometimes) movements, as they fit just right. I haven't tried off-brand Chinese ones, mainly Reuge Swiss ones, and Sankyo Japanese ones. There's tons of songs available of course, but the ones I really want are so incredibly hard to find. I think for almost $5000 you can get a company to make your own, with your own music, but then after that; there's still a minimum order, etc.
I'm also wanting to collect a few of these Musipix radio-styled music boxes, as they are a bit older and I believe the inspiration for the Fisher Price ones. They're always high dollar and hard to find. I still don't have one.