if you are referring to the mast rollers or carriage rollers?
they are made a certain size and also have a tapered slant to them so tracking in the channels shape. Also bearings may be damaged if they are not rolling, especially under a load.
It would have been more advisable to just replace them.
Also you may want to clean the channel tracks where the bearings contact, no grease.
Some tech's may grease the channels but they should only be greasing the side where the thrust blocks are (if there are any) and do not grease the actual roller track. (at least they aren't supposed to be greasing the contact tracks of the rollers).
The roller is supposed to be able to roll freely, putting grease creates a couple problems that will crop up later on, 1 - it attracts dirt with in the long run accelerates wear. 2 - it also creates a slick surface letting the bearing slide instead of rolling which will allow flat spots to wear into the outside band of the roller.
Now if you are not greasing the roller track and they are still getting flat spots then you have a bearing problem in the rollers.