Track cleaner engine EC1

[capntheo]

Hi - I recently bought a Bachmann Union Pacific track cleaning engine. It has the strangest combination of wheels including 3 sets of mini power wheels (front back and center) the middle of which are on some kind of articulated arms that allows them to move up and down. Additionally, of the 2 pairs of standard wheels, the drive pair is slotted and clearly requires some form of traction tire as without it just slides on the track. Any idea how this works and where to get these tires? I have tried O rings but the radius causes the wheels to fall off the track.