2009 Trackmaster Edward Cracked gear

Or Amazon, for example this post:  https://www.blueplastictracks.org/thread...l#pid67369

I expect the hole will be 2mm diameter, they usually are (sometimes given as 1.95mm in listings).

This thread is a classic: https://www.blueplastictracks.org/thread-3006.html
Fortunately there are far more seller listings with more detail in them now than there were even six years ago.

This is the most recent lot that I bought, used to successfully repair an on-top Plarail monorail