[Kevan]

Mm? Should the white guide flag have a spring? It has a long pillar in a short shaft with no fixing, so just drops up and down with gravity.

Other than that, the running gear side of it all seems ok 

It won't drop down unless the front end lifts, I'd set the front tyres to touch the track when the guide is fully up against the chassis.

...no spring on any I've bought or seen