Wooden toy vehicle, needs repair (Nepean)

This well loved toy needs somehow who is handier than I am with wood glue for a fix. Or, maybe someone who is creative would love a quality set of rubber wheels for another project? As you can see in the photos, there needs to be a knob to sit atop the pin. My failed fixes have resulted in the loss of the knob. Maybe you can give this otherwise very solid toy a second life?