Are the factory wheels in-gauge? I went through this with their AutoFlood hoppers - every axle was out-of-gauge, and the coupler screws needed to be recessed to keep from interfering with the outboard axle. Once those issues were addressed, they ran flawlessly.
Assuming there are no issue with the coupler screws, simply setting the gauge on the stock wheels sets may be all that's required to get them running smoothly and reliably.
Chris
