P2s

[AdamOrmorod4468]

I'm finding my 2005 to be particularly rear-heavy, not helped by the metal cartazzi and the lack of weight towards the front. They haven't even used the sloping weight from the 2013 version, presumably to make room for the smoke generator!

The front pony and driving wheels occasionally lift away from the track on bumps (my track is far from ideal, kato unitrack on a laminate floor, but this is the first loco I've ever had derail unprompted), but it's possible to gently push down on the front to bring all the wheels back into contact. I've also noticed that the front pony is having to turn quite a lot, suggesting to me that the loco is pivoting towards its read. Hopefully a bit of extra ballast towards the front with sort things out, I never noticed an issue with the old one. I don't have either 2002 or 2007 to see whether the die cast running plate makes any difference.

[Hatfield Shed]

The balance issue is interesting, but easily corrected as there is a void up front by the sound of it.

However, the coupled wheelbase will be rigid in typical RTR fashion, (with few exceptions) and if this model has the longest coupled wheelbase that you have yet operated, improving the track alignment is the better place to start. Floors in domestic premises are rarely plane, and yet more so when flooring products have been added on top, but I think you know that. This is why 'we' build raised layouts where the rail top level can be closely controlled; when can you start?

[AdamOrmorod4468]

The balance issue is interesting, but easily corrected as there is a void up front by the sound of it.

However, the coupled wheelbase will be rigid in typical RTR fashion, (with few exceptions) and if this model has the longest coupled wheelbase that you have yet operated, improving the track alignment is the better place to start. Floors in domestic premises are rarely plane, and yet more so when flooring products have been added on top, but I think you know that. This is why 'we' build raised layouts where the rail top level can be closely controlled; when can you start?

My old P2 has always been fine, which is why I was a little surprised and thought it worth mentioning.

I'm (I hope) halfway through my PhD, so it's going to be a little while before I can dare think about a permanent layout! Though scenery made out of imagination is at least very flexible

[Hatfield Shed]

That is worthy of mention, as most reports are that the new production is superior in pretty much all respects. Not that I will I have read all the online opinion...

Right with you on imaginary scenery. Cheap, maintenance free, infinitely variable, really, what's not to like?

[AdamOrmorod4468]

In the engine shed Hornby say "the locomotive has a well-balanced weight over the main drive axle", and caaaarefully balancing the loco on my fingers I would agree with them (assuming that by the "main" axle they mean the third one that is driven on the model). I would have thought that one would naïvely want the loco balanced between the second and third?

[Hatfield Shed]

Nothng naive about having the centre of mass as close to the centre of the coupled wheelbase as practical, particularly as there is rarely much in the way of springing on those axles, and unless the owner modifies the model, any carrying wheels with flanges supply relatively little guiding action, and a flangeless wheelset none at all except of the undesireable sort.
A little weight forward may be worthwhile.
Also worth trying the model without the flangeless wheelset, just in case this occasionally acts on a rail side.