Cthulhus wrote on Jul 12^th, 2009 at 6:57pm:

This is not a problem with the Necroscop fix or texture. the problem is that the FSX Overhead gauges are designed from a FS9 version and they are not "really" for FSX, ok they work but a FS9 gauge in FSX will don't have any illumination. The solution : Transform them in a FSX standard.

Seems so. But in 753 - all OK. Even the both models are using same textures and gauges. I think the reason is "materials" settings in VC for 752.
Any way - It can be fixed with additional "Panel" lightsource under overhead. I've played a bit with FX tools from SDK and yes, if the lightsource is lit-up - textures and gauges become visible.

Try to keep original lights.4 in aircraft.cfg probably it helps.
Here the good doc how it works: http://msdn.microsoft.com/en-us/library/cc526969.aspx

Unfortunatelly now I have no enough time to figure all this things out.
But if you have questions - feel free to ask.