re
that's were my problem is. I have a couple tight 18" turns on inclines. After laying the track and roadbed, I tested, then tweaked. Everything was ok. I then did some work to filling in between tracks for the base of scenery. Went back and had to adjust again because of either the roadbed or incline was not constant, had a half a millimeter dip. I went back adjusted again and tested. I ran the trains for more than couple hours with out any problems. Next I did the ballasting. Now back to the same problem same places. I made sure the rails were clean but it is the same as before. I have a couple GP 50's that do fine the way it is and I am just don't want to rip up that track and ballasting just for it to happen down the road. So I'm selling my sd's on ebay and I have my eye on a proto 2k gp 30. I have a couple GP 50's that don't have a problem. One Athearn and one Atlas.