Must be talking SD9?
The plastic Atlas frog can have a slight protrusion above the adjacent rail level. If you take off some of the roadbed, then the whole switch goes down, but it doesn't do anything to smooth the issue with the frog not mating with the rail. IIRC, the issue is solved by filing down the plastic to match the rail. There's some other stuff that people do with the frog to correct its issues, but I don't have any Atlas track so no direct experience with fixing that.
Mike Lehman
Urbana, IL
A GP-9 has 4 axles
I just saw a youtube video where the space between the guard rail was too narrow and caused the wheels pop up. It was Atlas but not all turnouts had the problem.
Henry
COB Potomac & Northern
Shenandoah Valley
ONLY my Paragon 3 GP9 derails at a turnout in the trailing point direction. The Atlas 2F & 2R (RS-1) and 282 Mikado do not. Something is lifting the rear wheels causing the 1st wheel set to jump over the rail. The turnout is a double curve Code 100 Atlas. I found that there was a bump as the wheels transverse do the frog so I filed the roadbed in that area down. And ran a wheel set over with no bump up. Still derails. PS: Wheelsets on loco and track in gage.
Gary