AF of my 70-200 f/4L and 400 f/5.6L making noise

[LSeries]

My (a couple of years old) 70-200 f/4L IS USM makes rubbing noise while autofocusing. You can clearly here the focus group moving inside the lens. Also the MF doesn't work anymore, it just slips. The AF at least feels very slow. I compared this to a similar lens of a friend and it was completely silent and the AF was fast. Does it need lubrication or something..?

Now I noticed, that also my 400 f/5.6L USM makes a similar rubbing noise while autofocusing. I swear it was completely silent before. Is it "normal" that you have to send your lenses to service due to this kind of AF issues?

 

[Mt Spokane Photography]

The inner mechanism rides on some nylon bushings that can break or be damaged. When that happens, AF slows down or even jams. I'd have it repaired, it might be something else or a combination of things. If you are adventuresome, you can possibly repair it, but if pieces of the bushing are not easy to remove, its better to have a experienced tech to repair and check it.

There may even be some tear down videos on youtube.