You're probably right Dave - let me guess, a repair isn't economical for such an old cam?
Also worse on a longer lens but still there on a shorter one.
This may not be any use, but Ive just had a Canon camcorder CCD replaced free of charge at Plymcare in Plymouth. All it cost was the postage, and the camera was well past the warranty (6ish years old).Plymcare: 01752 303555