@Darrell wow your original photo wasn't super-clear, I see it now. If yours has gears instead of a chain then it was either modded by a prior owner, or it's a rare early variant (and not too successful.)
If the gear tower is the only thing that's cracked, you're lucky. Check out this link: https://www.finescale360.com/p...?variant=43786730894
This aftermarket gear tower should be a "drop in" replacement for your existing one. The large lower sprocket also increases the gear ratio for excellent slow-speed performance. I would still add a flywheel. You can get one from Northwest Short Line (NWSL), from MTH parts, etc. If you can't find a flywheel with a bored recess that accommodates the U-joint collar, then substitute a dual-shaft motor and put the flywheel on the opposite shaft. It will work just as well. You might need to file a little flat spot(s) onto the motor shaft for the set screw to grip.
EDIT: After looking more closely, I don't think the replacement tower kit includes the upper shaft. You may or may not be able to fit the upper sprocket on yours in place of the gear. If it doesn't fit on yours, you'll have to order a new upper shaft from P&D. You'll have to order some chain from P&D, or directly from the company that makes it, Serv-o-link. You can also get dual-shaft Pittman motors from P&D. Good luck!
