ultrasonic cleaner. You can get an inexpensive one from Harbor Freight or Amazon.
•Cover bearings with Simple Green or an Orange Oil type degreasing liquid and run the cleaner for a few minutes.
•Yes… I know…another thing to bring to the track. But, while your bearings are being cleaned you are free to work on other things. Plus the ultrasonic is fantastic at cleaning gears, pulleys, pretty much anything on your car. Better than spending time with an X-acto picking rubber out of the pulleys.
•Remove the bearings and gently check how they feel (spin). If smooth, dab with a towel and let dry for a bit or gently blow with air. If not, run again in the cleaner.
•Once clean, add one drop of oil and check the feel again. If good, re-install