I seem to remember that it was due to the fitting of certain equipment behind the headcode box but wouldn't fit with the TGD in place so were replaced with small marker lights.
T-T
Unless it's been mentioned elsewhere on here or in the booklet (Packed away with the box) I didn't know that:
F1 engine start
F1/F1 Off engine fail to start
F1/F1 Off/F1 engine cold start (23 seconds)
Again, excellent model.
T-T