1. Take out all 4 wheels with Allen wrenches.
2. Wipe off the dirt from the wheels.
3. Clean off axles.
4. Clean the inside of the frame with a cloth.
5. Remove bearings from the wheels, with a safety pin, take off the rubber covers or shields from the bearings.
6. Wipe off the grime. Avoid using water, this will rust the bearings
7. Apply two drops of lubricant to each and put shields back on
8. Be sure to put spacer back between bearings before putting the wheels back in the frame.
9. Use one small drop of blue (removable) thread lock on the axle threads.
10. Install and tighten axles using Allen wrenches.