Taking lenses apart?

Hi all,
I have a Sigma 17-70mm which has noticeable piece of dust/debris behind the front element, I've tried a vaccum cleaner at the ring end and zoomed it in and out a bit to no avail.

Is there any way to remove the front element or get at the inside of it,I dont think it affects picture quality but would prefer to remove it before selling the lens.

If I was buying a lens I would not buy one that I knew the previous owner had opened, cleaned and reasesembled. Lens repairs are for the experts, so you may reduce the value of your item considerably. In any event it is likely that traces of your dismantling will be evident.

I'd leave well alone and just sell as it is.

Yes, I'm afraid I'll probably have to, I dont fancy paying experts prices.

You might be able to use a can of compressed air to clear it without needing to open anything.

Its worth a shot, especially if I can get the tube right in.

Trouble is you may just move the dust to somewhere worse or add to the problem by moving more dust around!

It may be worth having a go at a £5 old prime lens but zooms are horribly complicated and easy to muck up. One of those times where you can save a whole lot of money by not doing anything, unless you really know what your doing!

Only £25 to have it professionally cleaned, including RMSD return post:

http://swpp.co.uk/trade/goto/rd.cgi?redir=http://www.camerarepairs-r-us.co.uk

John