Okay TSR show me how I'm actually supposed to shade this

[Terminal Devastation]

Okay, I quickly whipped up this close up side view of a background tower in a background supplied to me (Henceforth will be refered as the original "ref" and isn't mine at all) for a sprite comicing competition than may or may not have had allowed things like bad background splices and sprite style mixing with no consequence.

tl;dr I made this knowing half assing the shading would be perfectly fine for its function.

Other information: Due to my convoluted method of making sure the proportions are correct this is likely an edit of the type resize-reshade, despite the fact I bothered to C+P jumbo scratched pixels to get the basic outline of the thing. So I wouldn't cheat with the shading too much.

Now TSR, I'm asking you how I should properly shade this mess, since I suck shading cylindrical things this large.

Self-critic tells me the light source is completly messed up and there is too much banding/possible pillowing. As to why I'm posting this before I tried fixing this, it is because I have little to no idea on how to actually begin to fix those on something of this scale and I'd like to avoid making other potential mistakes when I do go back to fix it.