It is now recommended to print the following two models:
usb-to-ps1-mouse-pro_top_ALL_PCB_REVISIONS.stl
usb-to-ps1-mouse-pro_bottom_ALL_PCB_REVISIONS.stl
The usb-to-ps1-mouse-pro_bottom_PCB_1_ONLY.stl only works with the PCB_1 revision of the board.
The author marked this model as their own original creation.