I have a Canon 24-70 f2.8L USM. It's the original model. I bought it used and noticed a drop of oil on the back element, so I followed a video and took it apart to clean it. After that, I noticed an issue with the focus. If the lens focus ring is turned to the left a whole or partial turn, then the auto focus doesn't respond. I have to turn it again slightly to the right to get the focus to work again. Occasionally, if I focus on a distant object, it will stop responding until I turn it to the right again. I'm assuming the left turn to focus is causing something to detach until it turns right again. Any thoughts on what to look for would be appreciated.
