Hi Smiffy. Can you give me an example. Missing parts is a common enough problem with some earlier 3rd party FS2002 aircraft in FS9 but I've never come across it in FS2002. ???

I suspect you might be referring to the Virtual Cockpit  (VC) or interior views of external parts from the cockpit. Some aircraft have a VC while others do not. This is a matter of preference for the author. If you want views of the engines & other parts of aircraft without a VC from the cockpit the only answer is to use a panel with these extra views incorporated in it like the one in the default Lear45. This is not a proper DVC as used on most of the other defaults & later 3rd party aircraft.

This will be caused by the animation used on earlier FS2002 models. The point is, do they work OK in the actual sim?

The answer is to find a later or updated version of these aircraft if possible, created with either Gmax or FSDS2.