If you notice that some of your bearings aren't spinning easily, it may be time to clean and lubricate them. Proper care of bearings will help them perform better and last longer. Here are some tips on cleaning and lubricating your bearings. First, if don't already have one, you should get a T-handle Allen wrench for removing the wheels. Use the edge of the wrench to push the spacer out of one of the wheels and then use that spacer to push out the spacers in the remaining wheels.
Most bearings have removable shields held in place by a C-ring.
Removing the shield allows better access for maintenance. Some bearings, such as Swiss bearings, have a plastic retaining ring on one side instead of a dust shield. After removing the bearings, use a needle or a small screwdriver to pry out the C-ring that holds in the dust cover on the side of the bearing. If your bearings are Swiss bearings, remove the plastic retaining ring. Soak the bearings in a solvent such as citrus solvent or Simple Green until all of the old grease is dissolved.