How to get the rear of a maglev train model past the magnetic wall, cogging point after being moved by an electromagnet from behind

10 yr old grandson has built a maglev train model with a track using 2x23x8mm neodymium magnets spaced 4mm apart and an electromagnet from a shortened 10M bolt, .5mm copper coils x 800, a 4xAA battery pack, 1N4004 diode and a momentary switch.
Starting with the rear train magnets just at the front edge of the bolt the train consistently moves only 2-2.5cm along the track. The rear magnets travel over bare track between the bolt and the first track magnets.
Only a physical push will move his train the full length of the track. Any suggestions?