The Support Tubes are chocked in place--a small step in T1000627.
The Support Tubes are lowered into cradles (chocks) by lowering the external scissors tables.  They are then secured, strapped down if you will, with wire cables to lugs on the chamber wall.  After the external support structure is next removed, further securing of the Support Tubes will then be done on the outside of the chamber.

Thanks to Mark, Nicole, Chris and JimW