I would just like to thank YesTor for his post and photographs which have really helped me.
First the disappointment - my 66 789 arrived with one of the yellow larger steps and one of the small black steps missing from the front and one of the smaller battery boxes detached. Fortunately as the steps were on the spare aprons in the detail bag I was able to replace them.
When it came to running, mine had a horrendous wobble. On closer examination of the loco on a flat surface I could see that not all the wheels were touching the ground - see first photo. Following what YesTor had done I identified 5 axle boxes that didn’t seem to align very well and removed them. All had glue over them and one in particular - the one at the bottom of the 2nd photo had lumpy glue all over it - once I cleaned them up and replaced them, the loco sits with all whees on the ground and the wobble has gone !
Clearly the glue around the axle boxes wasn’t allowing the bogie to sit as it should have done and caused wobbling due to the uneven glue on the AB shaft.
Now the good - It is a fantastic model - delightful infact when you look at all the pipe details, cab interior, overall heft and general presence of the loco. In particular the lighting and the sound are stand out features - the ability to switch off the rear lights and have the cab light extinguish when the loco moves are brilliant. I also love the way the wheel squeal works.
All in all it is a stunning model, I just wish I hadn't had to replace missing parts and take apart the axle boxes which did take the initial shine off, but now very happy with it.