wallpaper

Many thanks for all the advice over the years.  Recently bought a two story brick Georgian built in 1949.  In very good shape structurally.  The foyer has wallpaper which extends to the second floor landing and hall. After the pictures came down it is obvious the paper needs cleaning.  It hasn't faded, just gotten dingy over the years.  There are a few spots here and there as well.  My go to cleaning company doesn't want to touch it.  Recommended finding someone who has restored old homes.  A spot test on hidden area shows that wet method of cleaning will discolor and spot.  The paper is on tight even at the seams.  I can work around or live with the spots if it has to be but am wondering if there is a dry method of cleaning off the surface dirt.  Pictures attached.