engine - 1:00 pm on Oct 10, 2012 (gmt 0)

They'll all have a finite life: has it reached the end of its usable life?

If you use autofocus a great deal then it's something you want. If you're happy with manual focus, just keep on using it as is.

If you really love the lens, send it for repair.

If the new lens is going to cost about the same as the repair, you don't have a lot to lose if you give it a go and try the repair yourself, especially if you have an idea that it's fixable. If you can't fix it yourself, assuming you've not destroyed it, you can still take it in for the repair.