Quite a while ago,there was another posting re sensor cleaning and this site was mentioned.
www.intemos.com I forget who mentioned this site,but many,many thanks.I tried to clean a new 350D sensor with a wet swab used for specs,(the sensor was full of dust specks,only a one week into use).A huge disaster.I had been online and read the info from this company,also in the Canon EOS mag,there was an article on sensor cleaning,explaining how exactly to go about things.Yes,I sent for the swabs from intemos and cleaned the sensor.This week my 20D was full of dust spots(has been very windy here).So ,as I had no clean swabs I used the old ones-big mistake,it does say only use once(I keep the old ones for cleaning the dogs ears!!!).Today I received a new pack of swabs and yet again have made a reasonable job of cleaning a very dirty,badly marked sensor.I did buy the liquid and after two tries,quite good.I do not remove lenses from cameras,but did remove to add the extender whilst out of doors.
6mths ago I would not have dreamt of attempting to clean myself,but this company give explicit details of how to use their products,and yes,it worked.