It is a little unclear what you mean by "smoky", but in the hunt for anti-newton glass (detailed in other threads over the years) it was found that the anti-reflection picture frame glass had a bad effect on print sharpness and flare. Is that what you are describing? A picture, of the problem, is worth a thousand words as they say.
If necessary, it is probably possible to use mounting board to make a temporary replacement glassless neg-holder. Cut the apertures in two pieces, then add thicknesses to make the carrier "fat" enough to seat securely. This wouldn't win any prizes for alignment perfection but is quick and easy to do in an emergency. Slightly more permanent is a similar arrangement from plywood sheets, the thin sort available in modelmaking stores.
Another possibility could be very dirty condensers, though that would more likely give uneven lighting than a "smoky" result, simply because it happens above the neg and not below. Yet one more option, try stopping the lens down a couple of stops and compensating with lengthened time - it is always possible that the lens is damaged/dirty/awful.