Step 1- google to find product ID Google search "Lionelville zoo" = first hit http://www.lionel.com/products...elville-zoo-6-24180/ so 6-24180
Step2 go to Lionel support and enter the product ID you just found https://www.lionelsupport.com/ and again using 6-24180 gets us the detailed product page https://www.lionelsupport.com/...Barn-Lionelville-Zoo
And we get :
So we search for that listed alternate number and we get https://www.lionelsupport.com/...?keywords=6304150500
it too shows out of stock but at least we know what we are looking for- a pancake style motor
So one option, I find this DC motor only no gear
https://www.lionelsupport.com/...-ROUND-NO-HARDWARE_3
But more scrolling and looking and find this
https://www.lionelsupport.com/...TURE-ROUND-W-BRACKET
Gee, that looks a lot like the original motor doesn't it?