My brother bought this tape machine used and it had a broken Gear C which seams to be a common problem, since there are people selling replacements on ebay. I tried my best to model a replica of the gear and we managed to fix the tape machine. The center hole might be slightly too tight depending on your printer. It might be worth it to file it out with a 2mm drillbit untill the gear spins freely on the shaft.
I don't know enough about mechanics to guarantee that this gear is a perfect fit or if a 3d printed gear is the ideal fix for this, but it seems to work fine and its certainly better than the old broken one.
The author hasn't provided the model origin yet.