I'm pretty sure most of that

I'm pretty sure most of that model is regular styrene. However, "The broken parts mounted to the drivers are a gray plastic" gives me pause. I don't really know what parts you are referring to. The driver centers? The Baker valve gear hangars? The rods? The rods are the only things I see that I could reasonably call "gray" but they are metal. The valve gear hangars aren't really connected to the drivers, and they're black or very dark brown. The eccentric cranks are screwed to the main drivers, they look dark (like the valve gear hangars) but I'm pretty sure they're metal too, although I could be wrong. What's actually broken?

My cement of choice for styrene is Tamiya extra-thin. It is really good at following capillary action to get in between two styrene surfaces and weld them together almost invisibly. ( Amazon link here) It (or perhaps its jar) is also a bit better about not evaporating. In other words, it preserves pretty well compared to other similar brands such as Plastic Weld.

But none of these styrene solvents have any effect at all on metal parts, which is what I'm a bit suspicious that you're referring to.

I've looked on photos and the

I've looked on photos and the side rod seem to be gray. Do you mean them by "mounted to the drivers"?

If yes I wouldn't expext styrene but a better suited engineering plastic like Delrin. Gluing would be difficult and I wouldn't expect the glued parts to withstand running of the locomotive.

There are ways to bond Delrin and similar materials: https://www.instructables.com/How-to-glue-Delrin/
/> There are others.
Regards

It is the eccentric link on

It is the eccentric link on the driver wheel that is connected to the baker valve linkage and is defiantly a gray plastic.

The Eccentric crank on the

 The Eccentric crank on the far left

Thanks, I think the eccentric

Thanks, I think the eccentric crank is styrene. (I never considered the crank because mine is basically black.)