We have found that over time the floor to wall / floor to ceiling tube stands by Universal or Del Medical will become very loose and begin to sway vertically back and forth in the wall rail. We found one so bad once that it could have swayed enough laterally to allow the upper rollers to come out of the rail which would have caused the tube stand to fall to the ground. Most of the time this is caused by the three 1/4″ bolts that bolt the column to the floor stand becoming loose. These bolts are behind the front cover at the bottom of the column. These bolts need to be tightened periodically so we now check them during every biennial calibration.