I have a Trix G, let me take a look and see if I can come up with a solution.  I purchase the bulk of my train items from Klein's aka modelstrainstuff.com, they are a huge customer of Bachmann maybe a little comment to them will help.

Having the same issue.  Doesn't appear to be a solution for the average modeler.  The following is a reply I received from "Marty" (paraphrased) on the N Scale notes file;

"I used 2004s but there are two issues you need to deal with. First is that the opening in the pilot is not big enough, you need file to make room.

Second, the truck side frames are not attached to the driving wheels, they are free floating so the coupler will pull up on a long train. If the coupler sits at the perfect height when not moving, as soon as there is some strain on it the coupler will rise and disconnect. The longest I could pull a train was two feet on level track.

The space above the trucks is absolutely flat. What I did was stick a piece of double sided sticky foam tape to the top of the truck, do not remove the tape protection from the top of the foam. This keeps the trucks in contact with the track. I ran on my club layout for three hours with no problem and no uncoupling."

I appreciate Marty's work, but I don't want to re-engineer a locomotive that has a MSRP of $399. Bachmann please consider a correction to your design and make available to customers.