EF 70-200mm 1:4 L auto focusings problem

Hi,
I had this lens, 70-200mm 1:4 L, for about 2+ years and I purchased it used. It has never been dropped or even bumped hard, by me,...other than putting it in the case. I always use the hood and filter but recently it responds poorly in auto focus.
In auto focus it is constantly hunting, even in good lighting conditions.

I am about to send it off to be repaired but I wanted to know if there was an easy fix (i.e. some form of cleaning that may fix this).

Thanks
Kevin

What focusing settings are you using, AI servo might cause it to constantly hunt as it is always re-adjusting focus.

Thanks for the reply Red Snapper.

I use AI Servo because my subjects are moving.

Maxum wrote in post #14462259
Thanks for the reply Red Snapper.

I use AI Servo because my subjects are moving.

Then you should expect your lens to "hunt" all the time.

Yeah, try to put it in 'one shot' and see if it could lock on the target.

Ok, the subject is clearly in the center of lenses/view finder but refuses to lock on, hence my concern and it wasn't as bad as it is now. It is just a transitioning from one fuzzy blob to another fuzzy blob...continuously

I will try the 'one shot' later today...

Thank you all!!

Maxum wrote in post #14462305
Ok, the subject is clearly in the center of lenses/view finder but refuses to lock on, hence my concern ...

Servo mode never LOCKS ... it's always focusing. Are you using the back button focus? If so, if shooting a static subject, focus and let off the button. You don't need it to keep "hunting", it's where it needs to be.

Also, make sure you have the AF limit switch activated.