2 ideas, first, try putting track marks down towards where your going, give it something to aim at. Use navigate via trackmark.
When it gets stuck/stops use the on screen help (the ? mark top left ish) and check the points/switches are set ok. if not change them with the mouse.
If it still doesn't move use stop navigation and manually drive it through the signal then continue navigation.
If you add mc custom hudv2 to your session you'll be able to see ahead what the signals are.