Buzzing AF lens

[Chinny]

Hello everybody,
This is my first time posting on here,so please be gentle!
Here's my problem-I have a Sony A200 with a standard 18-70 zoom,and it's been absolutely fine for the few months I've had it...until this morning.
I switched it on and an unholy,violent BUZZZZ came out of the lens! I switched it off and the same noise happened again!
I've only ever taken the lens off once,when I first got the camera(it's the only lens I have),so I don't think any foreign bodies could've gotten in to jam the mechanism or dirty-up the contacts,which is kinda what it sounds like.
Can anyone help me figure out what the trouble might be?Has this happened to anyone else?
I'd like to avoid taking it in for expensive repairs if possible!

[OldClicker]

First, since I assume it's still under warrantee, take it back to get it checked out.

To try to diagnose it:

Does the zoom ring turn smoothly?

Put the camera on Manual Focus (slide switch on the front, I think). Does the focus ring turn smoothly?

Remove the lens and turn the camera on. Still make the noise? If not, put it back on. Noise again?

TF

[Chinny]

Unfortunately the missus got me the camera from a home-shopping catalogue,so although in theory I could return it,it would be such a huge hassle I'd rather explore other avenues first.
The zoom ring is pretty smooth still-perhaps not as silky as when brand new,but no actual roughness;same with the focus ring.There's probably a build-up of dust in there,but quite how much of a build-up it'd need to cause this I don't know.I've certainly not used it in any especially dirty environments,so household dust it would be.
Yes,taking the lens off the camera does prevent the noise and refitting it brings the buzzing back,so the glitch is definitely in the lens.If only I had a second lens I could see if that too buzzes,but no such luck...I guess that'd be something they'd try if I took it into Jessups or some-such highstreet emporium.

[Frog]

Definitly lens. Shouldn't have a dust problem inside, especially since it seldom came off the camera.
Did it ever get bumped/dropped?
Is it warranted by Sony?

[OldClicker]

Try this:

Remove the lens. Look on the back of the lens mount and just inside the body around the edge. In the body, there is a silver ring that goes all he way around that has a tab on it at about 2:30 when looking at it from the front. On the lens, there is an arc shaped slot with a little tab in it near the red alignment indicator. (These two tabs are what the camera uses to open/close the aperture in the lens.) Some times one of these tabs (usually in the body) gets stuck in the wrong position. In the body, it should be up against a little plastic stop. If not, gently try to push it back into position. In the lens it should be as far as it can go counterclockwise when viewed from the rear. If it isn't, you probably need a lens repair because it should just snap back into position, but you can get an even better lens for much less than a body.

This help?

TF