Hi all, I recently purchased a Greenfield Anniversary 88. It runs and cuts but needs a bit of TLC. I noticed the chain idler tension sprocket was just running loose on the mounting shaft. I believe it's missing a bearing. Would anyone know what type of bearing it needs and where I can buy one from? The mounting shaft diammeter is 12.7mm (1/2") and the inner diammeter of the sprocket is 17.4mm. Picture attached.