There is no way to edit a PDF file to fix a banding problem without access to the file which produced the PDF, sorry.
Sigh. That's what I was afraid of. The InDesign file pulls elements from an ems file that I don't have access to. Thank you.
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Not only can't you fix the such an issue in Acrobat, but it is very unclear whether even having access to the InDesign file would help you either.
Gradients created natively in InDesign use PDF smooth-shaded gradients which should not cause you any banding issues, unless you have a problematic RIP or printer.
But you mentioned that “the InDesign file pulls elements from an EMS file.” An EMS file is a eMachineShop CAD Design File. InDesign doesn't directly place such files, but it is entirely possible that whatever created the content in a CAD program likely was simulating gradients with either raster images or adjacent-slightly-varying-color narrow polygons. In either case, such “gradients” are very likely to have banding and other issues since they don't use PDF smooth-shaded gradients.
I've been trying to smooth it out in photoshop by isolating the the gradient area as a new layer. It's strange because I've had almost an identical file printing fine, but this one has far more banding when printed than last time. I've gotten most of the banding out but now there is a halo around the edge of the gradient area with a green tint (gradient is blues)