Thanks to all for helpful respones! There is no bump or irregularity so I think I have the connections right... I will try the filing technique tonight and see if that helps...

Thanks for the response. I had this issue elsewhere, with typical track-track connections, and was able to correct as you suggested.
However, this issue at the rerailer seems like a solid connection. It seems like part  of the problem is that the rerailer is  slightly elevated compared to the rest of the track, and the locomotive doesn't follow the very slight decline down to the typical track??

Hello,
I just set up my Bachmann ho scale Pacific flyer under the tree.
Problem is,  when  the locomotive comes around the rerailer piece, the front wheel often get derailed. This is more common at moderate and faster speeds, but I can observe it slightly at very slow speeds. Pulling cars behind it also does not seem to help, but also doesn't seem to have a significant effect on the situation.

Any ideas how to help keep  the wheels down on the track, especially in front?
Thanks for your help!