I have not read all the replies, so if I repeat some info forgive me. One thing that needs to be checked is the wheel spacing or gauging. I know that there are several gauges on the market these days. If the gauging is to tight/narrow or too wide this will cause problem when the car goes through the turn out. I have even run into a car that had a bent axle which will cause the same problem. Car weight is another spot that can cause problems, a car that is to light can bounce while going through a turn out. When trying to push a long string of cars through a turn out, the truck mounted coupler can sometimes be the problem. Be sure to check the track gauge through the turn out, once and awhile a turn out can be out of gauge. Also make sure if you have anchored the turn out to your layout table top that you did not secure it to tight, if it is to tight it can cause the track to bow inward and take it out of gauge.