Best way to clean a gold-plated yoyo bearing?
In most of the case distilled water is enough, but you should be sure that there are no salts inside your object if you can perform a Conductometry test on the washing water follow this procedure: Wash the item inside a buck for 3 minutes with distilled water measure Conductometry, take another bucket with the same amount of water wash the item for 3 minutes, measure Conductometry repeat these steps until conducibliy drop down.

This is a Conductometry test I've made while restoring an ancient metal object. You can see that I needed 5 washing to get good result. 


If you have high conductivity you should identify the salts with some spots test to understand where they came from.

If you have grease you can use a surfactant like Plysorbate 20 2% in distilled water not more!
Eventually if there to much salts and grease you can use: Thiourea solution 8-10% Sodium thiosulphate 30% EDTA 10 % (reference here).

Remember to dry very carefully the object with a hair dryer, NEVER leave the object wet for more than a couple of minutes!

Eventually you can use a protective like Soter or Zapon these normally cause in terms of colour change a $\Delta E$ of 2-4 so ask to your self if you really need it for a gold object. 

In my opinion avoid ultrasonic cleaning for composite materials! If you really care about the object ask for a metal restorer!