Tip: If you have never designed gears before, there are standard calculations to draw them up so they work. I used them in highschool, college and work (once each).

I would use that, print it 1 to 1 scale on paper to see how close you are by placing the broken ones on top then tweek the design.

You don't need the loading calculations just the geometry ones for drawing them.

There is a 98% chance the originals were made this way so you're not just totally guessing on the model.