I noticed on a couple of my Lionel Fastrack switches that the frog was slightly raised from the road bed causing the train and cars to tilt as they went through the frog. I don't know if this is a widespread issue or just my bad luck. I was able to quickly and easily resolve this issue. I'll apologize in advance if someone has posted about this before, but I was unable to find any articles on OGR or anywhere else about it.
Here's the switch before the fix. It's kind of hard to tell in the picture that the frog is slightly raised.
With the frog removed you can clearly see from the underside where the frog doesn't sit in all the way with the plastic piece.
Separating those two reveals the issue here, there is some flashing on the cast frog piece.
Using my Dremel I was able to remove the flashing.
With the two pieces reattached you can see how they meet flush together.
I hope this helps anyone with the same issue. The train looks better going through the switch when it's not tilting on the frog.