Hawk, greasing is probably the worst thing you could do as all the crud then sticks to the balls & makes it worse after one load sequence. Also you can't seal the units completely as they need to rotate & go up & down to absorb shock/weight.
There has always been a problem in the winter with those ballmats but this year has been the worst and maintenance can't keep up, either with the amount of work or spares provision. One example was mat changed one weekend & reported as bu**ered by Wednesday!
RT