*Please note with the "L" track design you may here some noises underneath the seating area. This is completely normal as the "L" track design causes a hollow base under the seating area which may cause some noises depending on users weight. You may also experience a slight lifting on one side of the rollers.  This is caused by the roller being caught on the protective cloth between the backrest padding.  This again is normal and does not happen often.  However, there is a retention spring which will bring the roller back to normal neutral positioning.