2009 Hiro Wheel issue

Picked up an used 2009 Trackmaster Hiro not long ago, haven't really run it.
I popped it open and put batteries in, and it seems to run fine, but it seems as though one of the drive wheels isn't spinning with the other.
If I lightly touch that wheel, it stays put while the other wheel turns with the axle.

Has this happened to anyone before? What can I do to remedy the situation?
Any help is appreciated.

[Super]

If the gear and other wheel are still turning its sounds to me like the one wheel may be stripped on the axle. You could take it apart and see for sure. If so, and if you have no spare replacement wheels, you could try a spot of Super Glue on the axle end and press the wheel back in place.

An excellent idea. Thanks Super!

if the wheel has spun off, you may need to rough up the end of the axle with a file to help the glue to take. dont go too far, just enough.