Mike
Same thing happened to me
On both the gg1 and the gs4
If I recall
I just didn’t replace them
I know for a fact the g unit runs fine
I can’t 1000000% recall if the gs4 was ok
But I kinda recall it was
Probably not much help to ya here
Carry on
Eric
While the GS4 will turn wheels without the traction tire, you do NOT want to run it for any extended period of time without tires. Lacking tires means that driver is a smaller diameter and will bounce up and down on the rails, and since the other three drivers are driven by the drive rods themselves, you'll be putting all kinds of weird stresses on the rod pins. At best, you'll disrupt the driver quarter, at worst you'll throw a pin off into the abyss.
@RBrodzinsky and I helped a guest operator on the Free-moN layout at the N Scale convention with this exact issue.