It sounds like your shutter needs a CLA, again you don't say where you are, a CLA is cheap in the US $30, but £50 in the UK and about the same in the EU in Euros.
Sometimes it's possible to do a simple clean yourself but it may not be your best option. But a couple of drops os Isopropyl alcohol on the shutter blades and firing the shutter a few times can sometimes work wonders.
I missed Mike's reply saying similar.
Last edited by Ian Grant; 02-21-2010 at 02:06 PM. Click to view previous post history.