Don,
To test the voltage on the switches, set your meter to read AC volts, and put one lead on the center rails, and the other lead goes to the outside rails that do NOT have the insulated pins in them.
These rails are the ground connection.
One rail would be the entire straight outside rail nearest the switch machine, and another would be the curved outside rail JUST OPPOSITE the switch machine.
The curved outside rail WITHOUT the insulating pin is also ground.
Lastly, the swivel points are also ground.

Turn up the power and measure the voltage at the transformer terminals, the lockon, and on the switches at the described locations.
The voltage readings should be the same, or within a volt difference. Any larger variation of voltage at any point needs to be investigated and corrected.

If your lighted car did not exhibit any problem on both the straight and curved paths of the switch, chances are the switches are receiving voltage properly. Check the voltages anyway, to insure you do not have any voltage drops anywhere.

When finished checking the voltages, run a locomotive slowly until it stops, and report back exactly where it stopped. Upload a picture of it if possible.

Larry