How do i know when my 70-200 mm 2.8l lens needs to be repaired

[ArnieJacob63]

I bought it used and have had it for 2 years and wanted to know how to tell if its not focusing ok and may need repaires 

[cicopo]

See

http://photography-on-the.net/forum/showthread.php?t=857871

[ebiggs1]

??????????????? Is it working ? 

Or is it just not working up to your expectations?

They are very tough and very reliable lenses.