2004 VE bogie wheels?

Got the new (to me) 144 Vertical Edge 600 and they gave me a extra set of wheels and I noticed just one plastic wheel off center inside on the back of the track. Trying to figure out if there should be two of the wheels on the inside back axle shaft at the rear. There is a wheel on the outside of the skids on both sides. Trying to figure out where the extra wheels should be mounted. I think the previous owner removed the wheels and mounted some scratchers, in place.

So should I leave the wheels off or remount them and move the scratchers back a bit.

Any advice would be appreciated.

Thanks
Bob

2004 VE bogie wheels?