On some online parts lists you can define what size the bearings are , then like @Buckster just order them from a bearing supplier. I use https://simplybearings.co.uk/shop/?msclkid=6bd2ee34478d1436eeea86681cec8f63&utm_source=bing&utm_medium=cpc&utm_campaign=Simply Bearings Brand&utm_term=simply bearings ltd&utm_content=Simply