To the right is an overall photo of the seismometer. The mass is the box-looking thing at the lower right, with the short tube extending out of it. The lvdt is under the mass at the right end of it, and contains three yellow sections. To the right of it is the connector for the electronics. In front and behind the mass are vertical square bars. These are stops that limit travel of the boom to prevent damage and keep the LVDT within its linear range. Partially hidden behind the mass is the cylindrical force-balance magnet with the coil inside it (completely hidden). The boom is the brass rod with the horizontal web soldered to it and the coil wires running along it. The triangular piece in the background is a stiffener for the base plate. Another one is normally attached to the near side of the base plate, but was removed for the photo. One of the pieces of dampening foam is visible on the mast support web at the upper left.
Below is a photo of the "business" end.