Re: e620 - blurry viewfinder
It could be a smudge on the mirror. When you look through the finder you are only seeing a reflection from through the lens. Take the lens off and look at the mirror. I wouldn't suggest cleaning it yourself though. Leave that for someone who knows what to do. Mirrors on modern DSLRs are delicate.
Re: e620 - blurry viewfinder
Did you try to adjust the diopter dial to suit your vision?.
Re: e620 - blurry viewfinder
Gotta be the diopter on the side of the pentaprism. Get you manual out and it will tell you how to adjust it so that the image is sharp in the viewfinder.