Had this with my 100-400L. I cleared it by forcefully turning the shade counter clockwise (has view looking at the lens cap). It will be really snug but it will move. Don't try rocking it, just turn it. As posted above, need about 1/th turn. It will ...
Last repair I had was January of 2018, completed by Canon Factory Services Center in Costa Mesa, CA.Total bill was $440.83 covering labor, parts and 2 day shipping.This is not a do it yourself project!
