By moving sound-absorbing foam sheets around the area between the dewar and the walls, we can see a difference in the vibration. My system has been modified by removing the diff pump and installing a turbo. Beware of ball bearing units. The Etec is far too susceptible to their vibrations. I have been using a Leybold maglev pump since they became available and can see no pump induced vibes below about 30Kx.
Vibration can be a nasty problem.
You can't assume they are coming from your area. When I was at George Washington Univ. Med School my lab was on the 5th. Never had problems with vibration until one day I was looking at cilia at 200,000 times and saw it. Zeiss came in to look at the scope and the surrounding area and couldn't find what was causing the problem.