Looks like your problem is going to be the pf repair, not the assembly. If you replace it, it will go in the same spot, so not sure how that helps you.
To fix it, get some skewers or dowel rods that fit tightly in the screw holes. Add a little wood glue and let it dry. When you reinstall, make sure to drill pilot holes so you don't rip out the repair with he screw.
Don't forget the spring. If you need to see how it is assembled, the upper trough should be the same or similar enough for you to figure it out.
You aren't going to find these parts, except from someone that's parting out a pf. I'm sure many different Williams games would work if you really want to replace it.